diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0cc21292ae..fcaeddd16c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,16 @@
+## [2.0.0-nullsafety.0] - March 5, 2021:
+* Nullsafety support
+* Official Flutter Web support
+* New features & fixes for lists:
+   * Support start attribute (e.g. `start="5";`)
+   * Support RTL direction
+   * Support setting padding - you can remove the starting padding if you choose
+   * Fixed unknown character box on iOS when font-weight is below w400
+* Upgraded link functions to provide more granular control
+* Fixed errors in text-decoration parsing
+* Fixed `<audio>` on iOS ("_duration called on null" exception)
+* Updated dependencies
+
 ## [1.3.0] - February 16, 2021:
 * New image loading API
 * Image loading with request headers, from relative paths and custom loading widget
diff --git a/README.md b/README.md
index 9c03d77918..296aec7437 100644
--- a/README.md
+++ b/README.md
@@ -171,7 +171,7 @@ Widget html = Html(
   data: """<p>
    Linking to <a href='https://github.com'>websites</a> has never been easier.
   </p>""",
-  onLinkTap: (String url) {
+  onLinkTap: (String? url, RenderContext context, Map<String, String> attributes, dom.Element? element) {
     //open URL in webview, or launch URL in browser, or any other logic here
   }
 );
@@ -197,10 +197,10 @@ Widget html = Html(
   <flutter horizontal></flutter>
   """,
   customRender: {
-      "bird": (RenderContext context, Widget child, Map<String, String> attributes, _) {
+      "bird": (RenderContext context, Widget child, Map<String, String> attributes, dom.Element? element) {
         return TextSpan(text: "🐦");
       },
-      "flutter": (RenderContext context, Widget child, Map<String, String> attributes, _) {
+      "flutter": (RenderContext context, Widget child, Map<String, String> attributes, dom.Element? element) {
         return FlutterLogo(
           style: (attributes['horizontal'] != null)
               ? FlutterLogoStyle.horizontal
@@ -227,26 +227,25 @@ Widget html = Html(
    <iframe src="https://www.youtube.com/embed/tgbNymZ7vqY"></iframe>
    """,
    customRender: {
-      "iframe": (RenderContext context, Widget child, Map<String, String> attributes, _) {
+      "iframe": (RenderContext context, Widget child, Map<String, String> attributes, dom.Element? element) {
          if (attributes != null) {
            double width = double.tryParse(attributes['width'] ?? "");
            double height = double.tryParse(attributes['height'] ?? "");
-           print(attributes['src']);
            return Container(
              width: width ?? (height ?? 150) * 2,
              height: height ?? (width ?? 300) / 2,
              child: WebView(
-                initialUrl: attributes['src'],
+                initialUrl: attributes['src'] ?? "about:blank",
                 javascriptMode: JavascriptMode.unrestricted,
                 //no need for scrolling gesture recognizers on embedded youtube, so set gestureRecognizers null
                 //on other iframe content scrolling might be necessary, so use VerticalDragGestureRecognizer
-                gestureRecognizers: attributes['src'].contains("youtube.com/embed") ? null : [
+                gestureRecognizers: attributes['src'] != null && attributes['src']!.contains("youtube.com/embed") ? null : [
                   Factory(() => VerticalDragGestureRecognizer())
                 ].toSet(),
                 navigationDelegate: (NavigationRequest request) async {
                 //no need to load any url besides the embedded youtube url when displaying embedded youtube, so prevent url loading
                 //on other iframe content allow all url loading
-                  if (attributes['src'].contains("youtube.com/embed")) {
+                  if (attributes['src'] != null && attributes['src']!.contains("youtube.com/embed")) {
                     if (!request.url.contains("youtube.com/embed")) {
                       return NavigationDecision.prevent;
                     } else {
@@ -293,7 +292,7 @@ A function that defines what the widget should do when an image is tapped.
 ```dart
 Widget html = Html(
   data: """<img alt='Google' src='https://www.google.com/images/branding/googlelogo/2x/googlelogo_color_92x30dp.png' />""",
-  onImageTap: (String url) {
+  onImageTap: (String? url, RenderContext context, Map<String, String> attributes, dom.Element? element) {
     //open image in webview, or launch image in browser, or any other logic here
   }
 );
@@ -432,8 +431,9 @@ A typical usage would look something like this:
 
 ```dart
 ImageSourceMatcher base64UriMatcher() => (attributes, element) =>
-    attributes["src"].startsWith("data:image") &&
-    attributes["src"].contains("base64,");
+    attributes["src"] != null &&
+    attributes["src"]!.startsWith("data:image") &&
+    attributes["src"]!.contains("base64,");
 ```
 
 In the above example, the matcher checks whether the image's `src` either starts with "data:image" or contains "base64,", since these indicate an image in base64 format.
@@ -448,10 +448,10 @@ ImageSourceMatcher networkSourceMatcher({
   String extension: "your extension",
 }) =>
     (attributes, element) {
-      final src = Uri.parse(attributes["src"]);
+      final src = Uri.parse(attributes["src"] ?? "about:blank");
       return schemas.contains(src.scheme) &&
-          (domains == null || domains.contains(src.host)) &&
-          (extension == null || src.path.endsWith(".$extension"));
+          domains.contains(src.host) &&
+          src.path.endsWith(".$extension");
     };
 ```
 
@@ -465,7 +465,8 @@ A typical usage might look like this:
 
 ```dart
 ImageRender base64ImageRender() => (context, attributes, element) {
-      final decodedImage = base64.decode(attributes["src"].split("base64,")[1].trim());
+      final decodedImage = base64.decode(attributes["src"] != null ?
+          attributes["src"].split("base64,")[1].trim() : "about:blank");
       return Image.memory(
         decodedImage,
       );
@@ -485,7 +486,7 @@ ImageRender networkImageRender({
 }) =>
     (context, attributes, element) {
       return Image.network(
-        attributes["src"],
+        attributes["src"] ?? "about:blank",
         headers: headers,
         width: width,
         height: height,
@@ -521,10 +522,10 @@ Widget html = Html(
     },
     networkSourceMatcher(): networkImageRender(
       headers: {"Custom-Header": "some-value"},
-      altWidget: (alt) => Text(alt),
+      altWidget: (alt) => Text(alt ?? ""),
       loadingWidget: () => Text("Loading..."),
     ),
-            (attr, _) => attr["src"] != null && attr["src"].startsWith("/wiki"):
+            (attr, _) => attr["src"] != null && attr["src"]!.startsWith("/wiki"):
     networkImageRender(
             mapUrl: (url) => "https://upload.wikimedia.org" + url),
   },
@@ -538,16 +539,17 @@ When an image with URL `flutter.dev` is detected, rather than displaying the ima
 2. Creating your own renders:
 ```dart
 ImageSourceMatcher classAndIdMatcher({String classToMatch, String idToMatch}) => (attributes, element) =>
-    attributes["class"].contains(classToMatch) ||
-    attributes["id"].contains(idToMatch);
+    attributes["class"] != null && attributes["id"] != null &&
+    (attributes["class"]!.contains(classToMatch) ||
+    attributes["id"]!.contains(idToMatch));
 
 ImageRender classAndIdRender({String classToMatch, String idToMatch}) => (context, attributes, element) {
-  if (attributes["class"].contains(classToMatch)) {
-    return Image.asset(attributes["src"]);
+  if (attributes["class"] != null && attributes["class"]!.contains(classToMatch)) {
+    return Image.asset(attributes["src"] ?? "about:blank");
   } else {
     return Image.network(
-      attributes["src"],
-      semanticLabel: attributes["longdesc"],
+      attributes["src"] ?? "about:blank",
+      semanticLabel: attributes["longdesc"] ?? "",
       width: attributes["width"],
       height: attributes["height"],
       color: context.style.color,
@@ -609,9 +611,7 @@ You can set the `navigationDelegate` of the webview with the `navigationDelegate
 
 ### Audio
 
-This package renders audio elements using the [`chewie_audio`](https://pub.dev/packages/chewie_audio) plugin. 
-
-Note: Audio elements currently do not work on iOS due to a bug with `chewie_audio`. Once [#509](https://github.com/Sub6Resources/flutter_html/pull/509) is merged, it will work again.
+This package renders audio elements using the [`chewie_audio`](https://pub.dev/packages/chewie_audio) plugin.
 
 The package considers the attributes `controls`, `loop`, `src`, `autoplay`, `width`, and `muted` when rendering the audio widget.
 
diff --git a/example/lib/main.dart b/example/lib/main.dart
index 85f6e9cf85..66bb38a3e7 100644
--- a/example/lib/main.dart
+++ b/example/lib/main.dart
@@ -19,7 +19,7 @@ class MyApp extends StatelessWidget {
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
+  MyHomePage({Key? key, required this.title}) : super(key: key);
 
   final String title;
 
@@ -157,13 +157,13 @@ class _MyHomePageState extends State<MyHomePage> {
             },
             networkSourceMatcher(domains: ["mydomain.com"]): networkImageRender(
               headers: {"Custom-Header": "some-value"},
-              altWidget: (alt) => Text(alt),
+              altWidget: (alt) => Text(alt ?? ""),
               loadingWidget: () => Text("Loading..."),
             ),
             // On relative paths starting with /wiki, prefix with a base url
-            (attr, _) => attr["src"] != null && attr["src"].startsWith("/wiki"):
+            (attr, _) => attr["src"] != null && attr["src"]!.startsWith("/wiki"):
                 networkImageRender(
-                    mapUrl: (url) => "https://upload.wikimedia.org" + url),
+                    mapUrl: (url) => "https://upload.wikimedia.org" + url!),
             // Custom placeholder image for broken links
             networkSourceMatcher(): networkImageRender(altWidget: (_) => FlutterLogo()),
           },
diff --git a/example/pubspec.yaml b/example/pubspec.yaml
index f5576e704f..73ff399401 100644
--- a/example/pubspec.yaml
+++ b/example/pubspec.yaml
@@ -4,7 +4,7 @@ description: flutter_html example app.
 version: 1.0.0+1
 
 environment:
-  sdk: ">=2.1.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
   flutter_html:
diff --git a/lib/flutter_html.dart b/lib/flutter_html.dart
index faf8468d3a..51bd6712c6 100644
--- a/lib/flutter_html.dart
+++ b/lib/flutter_html.dart
@@ -33,27 +33,27 @@ class Html extends StatelessWidget {
   /// **style** Pass in the style information for the Html here.
   /// See [its wiki page](https://github.com/Sub6Resources/flutter_html/wiki/Style) for more info.
   Html({
-    Key key,
-    @required this.data,
+    Key? key,
+    required this.data,
     this.onLinkTap,
-    this.customRender,
+    this.customRender = const {},
     this.customImageRenders = const {},
     this.onImageError,
     this.shrinkWrap = false,
     this.onImageTap,
     this.blacklistedElements = const [],
-    this.style,
+    this.style = const {},
     this.navigationDelegateForIframe,
   }) : super(key: key);
 
   final String data;
-  final OnTap onLinkTap;
+  final OnTap? onLinkTap;
   final Map<ImageSourceMatcher, ImageRender> customImageRenders;
-  final ImageErrorListener onImageError;
+  final ImageErrorListener? onImageError;
   final bool shrinkWrap;
 
   /// Properties for the Image widget that gets rendered by the rich text parser
-  final OnTap onImageTap;
+  final OnTap? onImageTap;
 
   final List<String> blacklistedElements;
 
@@ -67,11 +67,11 @@ class Html extends StatelessWidget {
   /// Decides how to handle a specific navigation request in the WebView of an
   /// Iframe. It's necessary to use the webview_flutter package inside the app
   /// to use NavigationDelegate.
-  final NavigationDelegate navigationDelegateForIframe;
+  final NavigationDelegate? navigationDelegateForIframe;
 
   @override
   Widget build(BuildContext context) {
-    final double width = shrinkWrap ? null : MediaQuery.of(context).size.width;
+    final double? width = shrinkWrap ? null : MediaQuery.of(context).size.width;
 
     return Container(
       width: width,
diff --git a/lib/html_parser.dart b/lib/html_parser.dart
index 2a4c1ea873..f12c67674f 100644
--- a/lib/html_parser.dart
+++ b/lib/html_parser.dart
@@ -17,42 +17,42 @@ import 'package:html/parser.dart' as htmlparser;
 import 'package:webview_flutter/webview_flutter.dart';
 
 typedef OnTap = void Function(
-    String url,
+    String? url,
     RenderContext context,
     Map<String, String> attributes,
-    dom.Element element,
+    dom.Element? element,
 );
 typedef CustomRender = dynamic Function(
   RenderContext context,
   Widget parsedChild,
   Map<String, String> attributes,
-  dom.Element element,
+  dom.Element? element,
 );
 
 class HtmlParser extends StatelessWidget {
   final String htmlData;
-  final OnTap onLinkTap;
-  final OnTap onImageTap;
-  final ImageErrorListener onImageError;
+  final OnTap? onLinkTap;
+  final OnTap? onImageTap;
+  final ImageErrorListener? onImageError;
   final bool shrinkWrap;
 
   final Map<String, Style> style;
   final Map<String, CustomRender> customRender;
   final Map<ImageSourceMatcher, ImageRender> imageRenders;
   final List<String> blacklistedElements;
-  final NavigationDelegate navigationDelegateForIframe;
+  final NavigationDelegate? navigationDelegateForIframe;
 
   HtmlParser({
-    @required this.htmlData,
-    this.onLinkTap,
-    this.onImageTap,
-    this.onImageError,
-    this.shrinkWrap,
-    this.style,
-    this.customRender,
-    this.imageRenders,
-    this.blacklistedElements,
-    this.navigationDelegateForIframe,
+    required this.htmlData,
+    required this.onLinkTap,
+    required this.onImageTap,
+    required this.onImageError,
+    required this.shrinkWrap,
+    required this.style,
+    required this.customRender,
+    required this.imageRenders,
+    required this.blacklistedElements,
+    required this.navigationDelegateForIframe,
   });
 
   @override
@@ -60,12 +60,11 @@ class HtmlParser extends StatelessWidget {
     dom.Document document = parseHTML(htmlData);
     StyledElement lexedTree = lexDomTree(
       document,
-      customRender?.keys?.toList() ?? [],
+      customRender.keys.toList(),
       blacklistedElements,
       navigationDelegateForIframe,
     );
-    StyledElement styledTree = applyCSS(lexedTree);
-    StyledElement inlineStyledTree = applyInlineStyles(styledTree);
+    StyledElement inlineStyledTree = applyInlineStyles(lexedTree);
     StyledElement customStyledTree = _applyCustomStyles(inlineStyledTree);
     StyledElement cascadedStyledTree = _cascadeStyles(customStyledTree);
     StyledElement cleanedTree = cleanTree(cascadedStyledTree);
@@ -73,7 +72,7 @@ class HtmlParser extends StatelessWidget {
       RenderContext(
         buildContext: context,
         parser: this,
-        style: Style.fromTextStyle(Theme.of(context).textTheme.bodyText2),
+        style: Style.fromTextStyle(Theme.of(context).textTheme.bodyText2!),
       ),
       cleanedTree,
     );
@@ -89,7 +88,7 @@ class HtmlParser extends StatelessWidget {
       renderContext: RenderContext(
         buildContext: context,
         parser: this,
-        style: Style.fromTextStyle(Theme.of(context).textTheme.bodyText2),
+        style: Style.fromTextStyle(Theme.of(context).textTheme.bodyText2!),
       ),
     );
   }
@@ -109,12 +108,13 @@ class HtmlParser extends StatelessWidget {
     dom.Document html,
     List<String> customRenderTags,
     List<String> blacklistedElements,
-    NavigationDelegate navigationDelegateForIframe,
+    NavigationDelegate? navigationDelegateForIframe,
   ) {
     StyledElement tree = StyledElement(
       name: "[Tree Root]",
-      children: new List<StyledElement>(),
+      children: <StyledElement>[],
       node: html.documentElement,
+      style: Style(),
     );
 
     html.nodes.forEach((node) {
@@ -137,9 +137,9 @@ class HtmlParser extends StatelessWidget {
     dom.Node node,
     List<String> customRenderTags,
     List<String> blacklistedElements,
-    NavigationDelegate navigationDelegateForIframe,
+    NavigationDelegate? navigationDelegateForIframe,
   ) {
-    List<StyledElement> children = List<StyledElement>();
+    List<StyledElement> children = <StyledElement>[];
 
     node.nodes.forEach((childNode) {
       children.add(_recursiveLexer(
@@ -152,7 +152,7 @@ class HtmlParser extends StatelessWidget {
 
     //TODO(Sub6Resources): There's probably a more efficient way to look this up.
     if (node is dom.Element) {
-      if (blacklistedElements?.contains(node.localName) ?? false) {
+      if (blacklistedElements.contains(node.localName)) {
         return EmptyContentElement();
       }
       if (STYLED_ELEMENTS.contains(node.localName)) {
@@ -173,47 +173,30 @@ class HtmlParser extends StatelessWidget {
         return EmptyContentElement();
       }
     } else if (node is dom.Text) {
-      return TextContentElement(text: node.text);
+      return TextContentElement(text: node.text, style: Style());
     } else {
       return EmptyContentElement();
     }
   }
 
-  ///TODO document
-  static StyledElement applyCSS(StyledElement tree) {
-    //Make sure style is never null.
-    if (tree.style == null) {
-      tree.style = Style();
-    }
-
-    tree.children?.forEach((e) => applyCSS(e));
-
-    return tree;
-  }
-
   static StyledElement applyInlineStyles(StyledElement tree) {
     if (tree.attributes.containsKey("style")) {
       tree.style = tree.style.merge(inlineCSSToStyle(tree.attributes['style']));
     }
 
-    tree.children?.forEach(applyInlineStyles);
+    tree.children.forEach(applyInlineStyles);
     return tree;
   }
 
   /// [applyCustomStyles] applies the [Style] objects passed into the [Html]
   /// widget onto the [StyledElement] tree, no cascading of styles is done at this point.
   StyledElement _applyCustomStyles(StyledElement tree) {
-    if (style == null) return tree;
     style.forEach((key, style) {
       if (tree.matchesSelector(key)) {
-        if (tree.style == null) {
-          tree.style = style;
-        } else {
-          tree.style = tree.style.merge(style);
-        }
+        tree.style = tree.style.merge(style);
       }
     });
-    tree.children?.forEach(_applyCustomStyles);
+    tree.children.forEach(_applyCustomStyles);
 
     return tree;
   }
@@ -221,7 +204,7 @@ class HtmlParser extends StatelessWidget {
   /// [_cascadeStyles] cascades all of the inherited styles down the tree, applying them to each
   /// child that doesn't specify a different style.
   StyledElement _cascadeStyles(StyledElement tree) {
-    tree.children?.forEach((child) {
+    tree.children.forEach((child) {
       child.style = tree.style.copyOnlyInherited(child.style);
       _cascadeStyles(child);
     });
@@ -253,20 +236,17 @@ class HtmlParser extends StatelessWidget {
     RenderContext newContext = RenderContext(
       buildContext: context.buildContext,
       parser: this,
-      style: context.style?.copyOnlyInherited(tree.style),
+      style: context.style.copyOnlyInherited(tree.style),
     );
 
-    if (customRender?.containsKey(tree.name) ?? false) {
-      final render = customRender[tree.name].call(
+    if (customRender.containsKey(tree.name)) {
+      final render = customRender[tree.name]!.call(
         newContext,
         ContainerSpan(
           newContext: newContext,
           style: tree.style,
           shrinkWrap: context.parser.shrinkWrap,
-          children: tree.children
-                  ?.map((tree) => parseTree(newContext, tree))
-                  ?.toList() ??
-              [],
+          children: tree.children.map((tree) => parseTree(newContext, tree)).toList(),
         ),
         tree.attributes,
         tree.element,
@@ -287,23 +267,20 @@ class HtmlParser extends StatelessWidget {
     }
 
     //Return the correct InlineSpan based on the element type.
-    if (tree.style?.display == Display.BLOCK) {
+    if (tree.style.display == Display.BLOCK) {
       return WidgetSpan(
         child: ContainerSpan(
           newContext: newContext,
           style: tree.style,
           shrinkWrap: context.parser.shrinkWrap,
-          children: tree.children
-                  ?.map((tree) => parseTree(newContext, tree))
-                  ?.toList() ??
-              [],
+          children: tree.children.map((tree) => parseTree(newContext, tree)).toList(),
         ),
       );
-    } else if (tree.style?.display == Display.LIST_ITEM) {
+    } else if (tree.style.display == Display.LIST_ITEM) {
       List<InlineSpan> getChildren(StyledElement tree) {
         InlineSpan tabSpan = WidgetSpan(child: Text("\t", textAlign: TextAlign.right));
-        List<InlineSpan> children = tree.children?.map((tree) => parseTree(newContext, tree))?.toList() ?? [];
-        if (tree.style?.listStylePosition == ListStylePosition.INSIDE) {
+        List<InlineSpan> children = tree.children.map((tree) => parseTree(newContext, tree)).toList();
+        if (tree.style.listStylePosition == ListStylePosition.INSIDE) {
           children.insert(0, tabSpan);
         }
         return children;
@@ -317,14 +294,13 @@ class HtmlParser extends StatelessWidget {
           child: Row(
             crossAxisAlignment: CrossAxisAlignment.start,
             mainAxisSize: MainAxisSize.min,
-            textDirection: tree.style?.direction,
+            textDirection: tree.style.direction,
             children: [
-              tree.style?.listStylePosition == ListStylePosition.OUTSIDE ||
-                  tree.style?.listStylePosition == null ?
+              tree.style.listStylePosition == ListStylePosition.OUTSIDE ?
               Padding(
-                padding: tree.style?.padding ?? EdgeInsets.only(left: tree.style?.direction != TextDirection.rtl ? 10.0 : 0.0, right: tree.style?.direction == TextDirection.rtl ? 10.0 : 0.0),
+                padding: tree.style.padding ?? EdgeInsets.only(left: tree.style.direction != TextDirection.rtl ? 10.0 : 0.0, right: tree.style.direction == TextDirection.rtl ? 10.0 : 0.0),
                 child: Text(
-                    newContext.style.markerContent,
+                    "${newContext.style.markerContent}",
                     textAlign: TextAlign.right,
                     style: newContext.style.generateTextStyle()
                 ),
@@ -332,11 +308,11 @@ class HtmlParser extends StatelessWidget {
               Text("\t", textAlign: TextAlign.right),
               Expanded(
                   child: Padding(
-                      padding: tree.style?.listStylePosition == ListStylePosition.INSIDE ?
-                        EdgeInsets.only(left: tree.style?.direction != TextDirection.rtl ? 10.0 : 0.0, right: tree.style?.direction == TextDirection.rtl ? 10.0 : 0.0) : EdgeInsets.zero,
+                      padding: tree.style.listStylePosition == ListStylePosition.INSIDE ?
+                        EdgeInsets.only(left: tree.style.direction != TextDirection.rtl ? 10.0 : 0.0, right: tree.style.direction == TextDirection.rtl ? 10.0 : 0.0) : EdgeInsets.zero,
                       child: StyledText(
                         textSpan: TextSpan(
-                          text: (tree.style?.listStylePosition ==
+                          text: (tree.style.listStylePosition ==
                               ListStylePosition.INSIDE)
                               ? '${newContext.style.markerContent}'
                               : null,
@@ -359,7 +335,7 @@ class HtmlParser extends StatelessWidget {
         return WidgetSpan(
           alignment: tree.alignment,
           baseline: TextBaseline.alphabetic,
-          child: tree.toWidget(context),
+          child: tree.toWidget(context)!,
         );
       }
     } else if (tree is InteractableElement) {
@@ -369,7 +345,7 @@ class HtmlParser extends StatelessWidget {
             text: childSpan.text,
             children: childSpan.children
                 ?.map((e) => addTaps(e, childStyle.merge(childSpan.style)))
-                ?.toList(),
+                .toList(),
             style: newContext.style.generateTextStyle().merge(
                 childSpan.style == null
                     ? childStyle
@@ -403,22 +379,21 @@ class HtmlParser extends StatelessWidget {
                 .map((childSpan) {
               return addTaps(childSpan,
                   newContext.style.generateTextStyle().merge(childSpan.style));
-            }).toList() ??
-            [],
+            }).toList(),
       );
     } else if (tree is LayoutElement) {
       return WidgetSpan(
-        child: tree.toWidget(context),
+        child: tree.toWidget(context)!,
       );
     } else if (tree.style.verticalAlign != null &&
         tree.style.verticalAlign != VerticalAlign.BASELINE) {
-      double verticalOffset;
+      late double verticalOffset;
       switch (tree.style.verticalAlign) {
         case VerticalAlign.SUB:
-          verticalOffset = tree.style.fontSize.size / 2.5;
+          verticalOffset = tree.style.fontSize!.size! / 2.5;
           break;
         case VerticalAlign.SUPER:
-          verticalOffset = tree.style.fontSize.size / -2.5;
+          verticalOffset = tree.style.fontSize!.size! / -2.5;
           break;
         default:
           break;
@@ -432,8 +407,7 @@ class HtmlParser extends StatelessWidget {
               style: newContext.style.generateTextStyle(),
               children: tree.children
                       .map((tree) => parseTree(newContext, tree))
-                      .toList() ??
-                  [],
+                      .toList(),
             ),
             style: newContext.style,
             renderContext: context,
@@ -456,12 +430,12 @@ class HtmlParser extends StatelessWidget {
   /// at https://www.w3.org/TR/css-text-3/
   /// and summarized at https://medium.com/@patrickbrosset/when-does-white-space-matter-in-html-b90e8a7cdd33
   static StyledElement _processInternalWhitespace(StyledElement tree) {
-    if ((tree.style?.whiteSpace ?? WhiteSpace.NORMAL) == WhiteSpace.PRE) {
+    if ((tree.style.whiteSpace ?? WhiteSpace.NORMAL) == WhiteSpace.PRE) {
       // Preserve this whitespace
     } else if (tree is TextContentElement) {
-      tree.text = _removeUnnecessaryWhitespace(tree.text);
+      tree.text = _removeUnnecessaryWhitespace(tree.text!);
     } else {
-      tree.children?.forEach(_processInternalWhitespace);
+      tree.children.forEach(_processInternalWhitespace);
     }
     return tree;
   }
@@ -491,18 +465,18 @@ class HtmlParser extends StatelessWidget {
     }
 
     if (tree is TextContentElement) {
-      if (wpc.data && tree.text.startsWith(' ')) {
-        tree.text = tree.text.replaceFirst(' ', '');
+      if (wpc.data && tree.text!.startsWith(' ')) {
+        tree.text = tree.text!.replaceFirst(' ', '');
       }
 
-      if (tree.text.endsWith(' ') || tree.text.endsWith('\n')) {
+      if (tree.text!.endsWith(' ') || tree.text!.endsWith('\n')) {
         wpc.data = true;
       } else {
         wpc.data = false;
       }
     }
 
-    tree.children?.forEach((e) => _processInlineWhitespaceRecursive(e, wpc));
+    tree.children.forEach((e) => _processInlineWhitespaceRecursive(e, wpc));
 
     return tree;
   }
@@ -537,19 +511,20 @@ class HtmlParser extends StatelessWidget {
   static StyledElement _processListCharactersRecursive(
       StyledElement tree, ListQueue<Context<int>> olStack) {
     if (tree.name == 'ol') {
-      olStack.add(Context((tree.attributes['start'] != null ? int.tryParse(tree.attributes['start']) ?? 1 : 1) - 1));
-    } else if (tree.style.display == Display.LIST_ITEM) {
-      switch (tree.style.listStyleType) {
+      olStack.add(Context((tree.attributes['start'] != null ? int.tryParse(tree.attributes['start'] ?? "") ?? 1 : 1) - 1));
+    } else if (tree.style.display == Display.LIST_ITEM && tree.style.listStyleType != null) {
+      switch (tree.style.listStyleType!) {
         case ListStyleType.DISC:
           tree.style.markerContent = '•';
           break;
         case ListStyleType.DECIMAL:
           olStack.last.data += 1;
           tree.style.markerContent = '${olStack.last.data}.';
+          break;
       }
     }
 
-    tree.children?.forEach((e) => _processListCharactersRecursive(e, olStack));
+    tree.children.forEach((e) => _processListCharactersRecursive(e, olStack));
 
     if (tree.name == 'ol') {
       olStack.removeLast();
@@ -562,15 +537,15 @@ class HtmlParser extends StatelessWidget {
   /// the list of the trees children according to the `before` and `after` Style
   /// properties.
   static StyledElement _processBeforesAndAfters(StyledElement tree) {
-    if (tree.style?.before != null) {
-      tree.children?.insert(
+    if (tree.style.before != null) {
+      tree.children.insert(
           0, TextContentElement(text: tree.style.before, style: tree.style));
     }
-    if (tree.style?.after != null) {
+    if (tree.style.after != null) {
       tree.children
-          ?.add(TextContentElement(text: tree.style.after, style: tree.style));
+          .add(TextContentElement(text: tree.style.after, style: tree.style));
     } else {
-      tree.children?.forEach(_processBeforesAndAfters);
+      tree.children.forEach(_processBeforesAndAfters);
     }
     return tree;
   }
@@ -587,7 +562,7 @@ class HtmlParser extends StatelessWidget {
   /// (4) Top and Bottom margins of a box with a height of zero or no in-flow children.
   static StyledElement _collapseMargins(StyledElement tree) {
     //Short circuit if we've reached a leaf of the tree
-    if (tree.children == null || tree.children.isEmpty) {
+    if (tree.children.isEmpty) {
       // Handle case (4) from above.
       if ((tree.style.height ?? 0) == 0) {
         tree.style.margin = EdgeInsets.zero;
@@ -596,7 +571,7 @@ class HtmlParser extends StatelessWidget {
     }
 
     //Collapsing should be depth-first.
-    tree.children?.forEach(_collapseMargins);
+    tree.children.forEach(_collapseMargins);
 
     //The root boxes do not collapse.
     if (tree.name == '[Tree Root]' || tree.name == 'html') {
@@ -614,7 +589,7 @@ class HtmlParser extends StatelessWidget {
       if (tree.style.margin == null) {
         tree.style.margin = EdgeInsets.only(top: newOuterMarginTop);
       } else {
-        tree.style.margin = tree.style.margin.copyWith(top: newOuterMarginTop);
+        tree.style.margin = tree.style.margin!.copyWith(top: newOuterMarginTop);
       }
 
       // And remove the child's margin
@@ -622,7 +597,7 @@ class HtmlParser extends StatelessWidget {
         tree.children.first.style.margin = EdgeInsets.zero;
       } else {
         tree.children.first.style.margin =
-            tree.children.first.style.margin.copyWith(top: 0);
+            tree.children.first.style.margin!.copyWith(top: 0);
       }
     }
 
@@ -638,7 +613,7 @@ class HtmlParser extends StatelessWidget {
         tree.style.margin = EdgeInsets.only(bottom: newOuterMarginBottom);
       } else {
         tree.style.margin =
-            tree.style.margin.copyWith(bottom: newOuterMarginBottom);
+            tree.style.margin!.copyWith(bottom: newOuterMarginBottom);
       }
 
       // And remove the child's margin
@@ -646,7 +621,7 @@ class HtmlParser extends StatelessWidget {
         tree.children.last.style.margin = EdgeInsets.zero;
       } else {
         tree.children.last.style.margin =
-            tree.children.last.style.margin.copyWith(bottom: 0);
+            tree.children.last.style.margin!.copyWith(bottom: 0);
       }
     }
 
@@ -662,7 +637,7 @@ class HtmlParser extends StatelessWidget {
           tree.children[i - 1].style.margin =
               EdgeInsets.only(bottom: newInternalMargin);
         } else {
-          tree.children[i - 1].style.margin = tree.children[i - 1].style.margin
+          tree.children[i - 1].style.margin = tree.children[i - 1].style.margin!
               .copyWith(bottom: newInternalMargin);
         }
 
@@ -671,7 +646,7 @@ class HtmlParser extends StatelessWidget {
               EdgeInsets.only(top: newInternalMargin);
         } else {
           tree.children[i].style.margin =
-              tree.children[i].style.margin.copyWith(top: newInternalMargin);
+              tree.children[i].style.margin!.copyWith(top: newInternalMargin);
         }
       }
     }
@@ -685,17 +660,17 @@ class HtmlParser extends StatelessWidget {
   /// or any block-level [TextContentElement] that contains only whitespace and doesn't follow
   /// a block element or a line break.
   static StyledElement _removeEmptyElements(StyledElement tree) {
-    List<StyledElement> toRemove = new List<StyledElement>();
+    List<StyledElement> toRemove = <StyledElement>[];
     bool lastChildBlock = true;
-    tree.children?.forEach((child) {
+    tree.children.forEach((child) {
       if (child is EmptyContentElement || child is EmptyLayoutElement) {
         toRemove.add(child);
-      } else if (child is TextContentElement && (child.text.isEmpty)) {
+      } else if (child is TextContentElement && (child.text!.isEmpty)) {
         toRemove.add(child);
       } else if (child is TextContentElement &&
           child.style.whiteSpace != WhiteSpace.PRE &&
           tree.style.display == Display.BLOCK &&
-          child.text.trim().isEmpty &&
+          child.text!.trim().isEmpty &&
           lastChildBlock) {
         toRemove.add(child);
       } else if (child.style.display == Display.NONE) {
@@ -709,7 +684,7 @@ class HtmlParser extends StatelessWidget {
           child.style.display == Display.LIST_ITEM ||
           (child is TextContentElement && child.text == '\n'));
     });
-    tree.children?.removeWhere((element) => toRemove.contains(element));
+    tree.children.removeWhere((element) => toRemove.contains(element));
 
     return tree;
   }
@@ -717,12 +692,12 @@ class HtmlParser extends StatelessWidget {
   /// [_processFontSize] changes percent-based font sizes (negative numbers in this implementation)
   /// to pixel-based font sizes.
   static StyledElement _processFontSize(StyledElement tree) {
-    double parentFontSize = tree.style?.fontSize?.size ?? FontSize.medium.size;
+    double? parentFontSize = tree.style.fontSize?.size ?? FontSize.medium.size;
 
-    tree.children?.forEach((child) {
-      if ((child.style.fontSize?.size ?? parentFontSize) < 0) {
+    tree.children.forEach((child) {
+      if ((child.style.fontSize?.size ?? parentFontSize)! < 0) {
         child.style.fontSize =
-            FontSize(parentFontSize * -child.style.fontSize.size);
+            FontSize(parentFontSize! * -child.style.fontSize!.size!);
       }
 
       _processFontSize(child);
@@ -741,9 +716,9 @@ class RenderContext {
   final Style style;
 
   RenderContext({
-    this.buildContext,
-    this.parser,
-    this.style,
+    required this.buildContext,
+    required this.parser,
+    required this.style,
   });
 }
 
@@ -752,8 +727,8 @@ class RenderContext {
 /// A [ContainerSpan] can have a border, background color, height, width, padding, and margin
 /// and can represent either an INLINE or BLOCK-level element.
 class ContainerSpan extends StatelessWidget {
-  final Widget child;
-  final List<InlineSpan> children;
+  final Widget? child;
+  final List<InlineSpan>? children;
   final Style style;
   final RenderContext newContext;
   final bool shrinkWrap;
@@ -761,8 +736,8 @@ class ContainerSpan extends StatelessWidget {
   ContainerSpan({
     this.child,
     this.children,
-    this.style,
-    this.newContext,
+    required this.style,
+    required this.newContext,
     this.shrinkWrap = false,
   });
 
@@ -770,14 +745,14 @@ class ContainerSpan extends StatelessWidget {
   Widget build(BuildContext _) {
     return Container(
       decoration: BoxDecoration(
-        border: style?.border,
-        color: style?.backgroundColor,
+        border: style.border,
+        color: style.backgroundColor,
       ),
-      height: style?.height,
-      width: style?.width,
-      padding: style?.padding,
-      margin: style?.margin,
-      alignment: shrinkWrap ? null : style?.alignment,
+      height: style.height,
+      width: style.width,
+      padding: style.padding,
+      margin: style.margin,
+      alignment: shrinkWrap ? null : style.alignment,
       child: child ??
           StyledText(
             textSpan: TextSpan(
@@ -798,10 +773,10 @@ class StyledText extends StatelessWidget {
   final RenderContext renderContext;
 
   const StyledText({
-    this.textSpan,
-    this.style,
+    required this.textSpan,
+    required this.style,
     this.textScaleFactor = 1.0,
-    this.renderContext,
+    required this.renderContext,
   });
 
   @override
@@ -818,7 +793,7 @@ class StyledText extends StatelessWidget {
     );
   }
 
-  double calculateWidth(Display display, RenderContext context) {
+  double? calculateWidth(Display? display, RenderContext context) {
     if ((display == Display.BLOCK || display == Display.LIST_ITEM) && !renderContext.parser.shrinkWrap) {
       return double.infinity;
     }
diff --git a/lib/image_render.dart b/lib/image_render.dart
index 94c5a73f79..9ba5b120e4 100644
--- a/lib/image_render.dart
+++ b/lib/image_render.dart
@@ -8,23 +8,23 @@ import 'package:html/dom.dart' as dom;
 
 typedef ImageSourceMatcher = bool Function(
   Map<String, String> attributes,
-  dom.Element element,
+  dom.Element? element,
 );
 
 ImageSourceMatcher base64DataUriMatcher() => (attributes, element) =>
     _src(attributes) != null &&
-    _src(attributes).startsWith("data:image") &&
-    _src(attributes).contains("base64,");
+    _src(attributes)!.startsWith("data:image") &&
+    _src(attributes)!.contains("base64,");
 
 ImageSourceMatcher networkSourceMatcher({
   List<String> schemas: const ["https", "http"],
-  List<String> domains,
-  String extension,
+  List<String>? domains,
+  String? extension,
 }) =>
     (attributes, element) {
       if (_src(attributes) == null) return false;
       try {
-        final src = Uri.parse(_src(attributes));
+        final src = Uri.parse(_src(attributes)!);
         return schemas.contains(src.scheme) &&
             (domains == null || domains.contains(src.host)) &&
             (extension == null || src.path.endsWith(".$extension"));
@@ -34,21 +34,21 @@ ImageSourceMatcher networkSourceMatcher({
     };
 
 ImageSourceMatcher assetUriMatcher() => (attributes, element) =>
-    _src(attributes) != null && _src(attributes).startsWith("asset:");
+    _src(attributes) != null && _src(attributes)!.startsWith("asset:");
 
-typedef ImageRender = Widget Function(
+typedef ImageRender = Widget? Function(
   RenderContext context,
   Map<String, String> attributes,
-  dom.Element element,
+  dom.Element? element,
 );
 
 ImageRender base64ImageRender() => (context, attributes, element) {
       final decodedImage =
-          base64.decode(_src(attributes).split("base64,")[1].trim());
+          base64.decode(_src(attributes)!.split("base64,")[1].trim());
       precacheImage(
         MemoryImage(decodedImage),
         context.buildContext,
-        onError: (exception, StackTrace stackTrace) {
+        onError: (exception, StackTrace? stackTrace) {
           context.parser.onImageError?.call(exception, stackTrace);
         },
       );
@@ -65,12 +65,12 @@ ImageRender base64ImageRender() => (context, attributes, element) {
     };
 
 ImageRender assetImageRender({
-  double width,
-  double height,
+  double? width,
+  double? height,
 }) =>
     (context, attributes, element) {
-      final assetPath = _src(attributes).replaceFirst('asset:', '');
-      if (_src(attributes).endsWith(".svg")) {
+      final assetPath = _src(attributes)!.replaceFirst('asset:', '');
+      if (_src(attributes)!.endsWith(".svg")) {
         return SvgPicture.asset(assetPath);
       } else {
         return Image.asset(
@@ -89,22 +89,22 @@ ImageRender assetImageRender({
     };
 
 ImageRender networkImageRender({
-  Map<String, String> headers,
-  String Function(String) mapUrl,
-  double width,
-  double height,
-  Widget Function(String) altWidget,
-  Widget Function() loadingWidget,
+  Map<String, String>? headers,
+  String Function(String?)? mapUrl,
+  double? width,
+  double? height,
+  Widget Function(String?)? altWidget,
+  Widget Function()? loadingWidget,
 }) =>
     (context, attributes, element) {
-      final src = mapUrl?.call(_src(attributes)) ?? _src(attributes);
+      final src = mapUrl?.call(_src(attributes)) ?? _src(attributes)!;
       precacheImage(
         NetworkImage(
           src,
           headers: headers,
         ),
         context.buildContext,
-        onError: (exception, StackTrace stackTrace) {
+        onError: (exception, StackTrace? stackTrace) {
           context.parser.onImageError?.call(exception, stackTrace);
         },
       );
@@ -142,7 +142,7 @@ ImageRender networkImageRender({
             return Image.network(
               src,
               headers: headers,
-              width: width ?? _width(attributes) ?? snapshot.data.width,
+              width: width ?? _width(attributes) ?? snapshot.data!.width,
               height: height ?? _height(attributes),
               frameBuilder: (ctx, child, frame, _) {
                 if (frame == null) {
@@ -164,7 +164,7 @@ ImageRender networkImageRender({
     };
 
 ImageRender svgNetworkImageRender() => (context, attributes, element) {
-      return SvgPicture.network(attributes["src"]);
+      return SvgPicture.network(_src(attributes)!);
     };
 
 final Map<ImageSourceMatcher, ImageRender> defaultImageRenders = {
@@ -174,20 +174,20 @@ final Map<ImageSourceMatcher, ImageRender> defaultImageRenders = {
   networkSourceMatcher(): networkImageRender(),
 };
 
-String _src(Map<String, String> attributes) {
+String? _src(Map<String, String> attributes) {
   return attributes["src"];
 }
 
-String _alt(Map<String, String> attributes) {
+String? _alt(Map<String, String> attributes) {
   return attributes["alt"];
 }
 
-double _height(Map<String, String> attributes) {
+double? _height(Map<String, String> attributes) {
   final heightString = attributes["height"];
-  return heightString == null ? heightString : double.tryParse(heightString);
+  return heightString == null ? heightString as double? : double.tryParse(heightString);
 }
 
-double _width(Map<String, String> attributes) {
+double? _width(Map<String, String> attributes) {
   final widthString = attributes["width"];
-  return widthString == null ? widthString : double.tryParse(widthString);
+  return widthString == null ? widthString as double? : double.tryParse(widthString);
 }
diff --git a/lib/src/css_parser.dart b/lib/src/css_parser.dart
index 6f6244639a..1cb30ca6d3 100644
--- a/lib/src/css_parser.dart
+++ b/lib/src/css_parser.dart
@@ -5,85 +5,92 @@ import 'package:csslib/parser.dart' as cssparser;
 import 'package:flutter/cupertino.dart';
 import 'package:flutter_html/style.dart';
 
-Style declarationsToStyle(Map<String, List<css.Expression>> declarations) {
+Style declarationsToStyle(Map<String?, List<css.Expression>> declarations) {
   Style style = new Style();
   declarations.forEach((property, value) {
-    switch (property) {
-      case 'background-color':
-        style.backgroundColor = ExpressionMapping.expressionToColor(value.first);
-        break;
-      case 'color':
-        style.color = ExpressionMapping.expressionToColor(value.first);
-        break;
-      case 'direction':
-        style.direction = ExpressionMapping.expressionToDirection(value.first);
-        break;
-      case 'display':
-        style.display = ExpressionMapping.expressionToDisplay(value.first);
-        break;
-      case 'line-height':
-        style.lineHeight = ExpressionMapping.expressionToLineHeight(value.first);
-        break;
-      case 'font-family':
-        style.fontFamily = ExpressionMapping.expressionToFontFamily(value.first);
-        break;
-      case 'font-feature-settings':
-        style.fontFeatureSettings = ExpressionMapping.expressionToFontFeatureSettings(value);
-        break;
-      case 'font-size':
-        style.fontSize = ExpressionMapping.expressionToFontSize(value.first);
-        break;
-      case 'font-style':
-        style.fontStyle = ExpressionMapping.expressionToFontStyle(value.first);
-        break;
-      case 'font-weight':
-        style.fontWeight = ExpressionMapping.expressionToFontWeight(value.first);
-        break;
-      case 'text-align':
-        style.textAlign = ExpressionMapping.expressionToTextAlign(value.first);
-        break;
-      case 'text-decoration':
-        List<css.LiteralTerm> textDecorationList  = value.whereType<css.LiteralTerm>().toList();
-        /// List<css.LiteralTerm> might include other values than the ones we want for [textDecorationList], so make sure to remove those before passing it to [ExpressionMapping]
-        textDecorationList.removeWhere((element) => element.text != "none" && element.text != "overline" && element.text != "underline" && element.text != "line-through");
-        css.Expression textDecorationColor = value.firstWhere((element) => element is css.HexColorTerm || element is css.FunctionTerm, orElse: () => null);
-        List<css.LiteralTerm> potentialStyles = value.whereType<css.LiteralTerm>().toList();
-        /// List<css.LiteralTerm> might include other values than the ones we want for [textDecorationStyle], so make sure to remove those before passing it to [ExpressionMapping]
-        potentialStyles.removeWhere((element) => element.text != "solid" && element.text != "double" && element.text != "dashed" && element.text != "dotted" && element.text != "wavy");
-        css.LiteralTerm textDecorationStyle = potentialStyles.isNotEmpty ? potentialStyles?.last : null;
-        style.textDecoration = ExpressionMapping.expressionToTextDecorationLine(textDecorationList);
-        if (textDecorationColor != null) style.textDecorationColor = ExpressionMapping.expressionToColor(textDecorationColor);
-        if (textDecorationStyle != null) style.textDecorationStyle = ExpressionMapping.expressionToTextDecorationStyle(textDecorationStyle);
-        break;
-      case 'text-decoration-color':
-        style.textDecorationColor = ExpressionMapping.expressionToColor(value.first);
-        break;
-      case 'text-decoration-line':
-        style.textDecoration = ExpressionMapping.expressionToTextDecorationLine(value);
-        break;
-      case 'text-decoration-style':
-        style.textDecorationStyle = ExpressionMapping.expressionToTextDecorationStyle(value.first);
-        break;
-      case 'text-shadow':
-        style.textShadow = ExpressionMapping.expressionToTextShadow(value);
-        break;
+    if (value.isNotEmpty) {
+      switch (property) {
+        case 'background-color':
+          style.backgroundColor = ExpressionMapping.expressionToColor(value.first) ?? style.backgroundColor;
+          break;
+        case 'color':
+          style.color = ExpressionMapping.expressionToColor(value.first) ?? style.color;
+          break;
+        case 'direction':
+          style.direction = ExpressionMapping.expressionToDirection(value.first);
+          break;
+        case 'display':
+          style.display = ExpressionMapping.expressionToDisplay(value.first);
+          break;
+        case 'line-height':
+          style.lineHeight = ExpressionMapping.expressionToLineHeight(value.first);
+          break;
+        case 'font-family':
+          style.fontFamily = ExpressionMapping.expressionToFontFamily(value.first) ?? style.fontFamily;
+          break;
+        case 'font-feature-settings':
+          style.fontFeatureSettings = ExpressionMapping.expressionToFontFeatureSettings(value);
+          break;
+        case 'font-size':
+          style.fontSize = ExpressionMapping.expressionToFontSize(value.first) ?? style.fontSize;
+          break;
+        case 'font-style':
+          style.fontStyle = ExpressionMapping.expressionToFontStyle(value.first);
+          break;
+        case 'font-weight':
+          style.fontWeight = ExpressionMapping.expressionToFontWeight(value.first);
+          break;
+        case 'text-align':
+          style.textAlign = ExpressionMapping.expressionToTextAlign(value.first);
+          break;
+        case 'text-decoration':
+          List<css.LiteralTerm?>? textDecorationList = value.whereType<css.LiteralTerm>().toList();
+          /// List<css.LiteralTerm> might include other values than the ones we want for [textDecorationList], so make sure to remove those before passing it to [ExpressionMapping]
+          textDecorationList.removeWhere((element) => element != null && element.text != "none"
+              && element.text != "overline" && element.text != "underline" && element.text != "line-through");
+          List<css.Expression?>? nullableList = value;
+          css.Expression? textDecorationColor = nullableList.firstWhere(
+                  (css.Expression? element) => element is css.HexColorTerm || element is css.FunctionTerm, orElse: () => null);
+          List<css.LiteralTerm?>? potentialStyles = value.whereType<css.LiteralTerm>().toList();
+          /// List<css.LiteralTerm> might include other values than the ones we want for [textDecorationStyle], so make sure to remove those before passing it to [ExpressionMapping]
+          potentialStyles.removeWhere((element) => element != null && element.text != "solid"
+              && element.text != "double" && element.text != "dashed" && element.text != "dotted" && element.text != "wavy");
+          css.LiteralTerm? textDecorationStyle = potentialStyles.isNotEmpty ? potentialStyles.last : null;
+          style.textDecoration = ExpressionMapping.expressionToTextDecorationLine(textDecorationList);
+          if (textDecorationColor != null) style.textDecorationColor = ExpressionMapping.expressionToColor(textDecorationColor)
+              ?? style.textDecorationColor;
+          if (textDecorationStyle != null) style.textDecorationStyle = ExpressionMapping.expressionToTextDecorationStyle(textDecorationStyle);
+          break;
+        case 'text-decoration-color':
+          style.textDecorationColor = ExpressionMapping.expressionToColor(value.first) ?? style.textDecorationColor;
+          break;
+        case 'text-decoration-line':
+          style.textDecoration = ExpressionMapping.expressionToTextDecorationLine(value as List<css.LiteralTerm>);
+          break;
+        case 'text-decoration-style':
+          style.textDecorationStyle = ExpressionMapping.expressionToTextDecorationStyle(value.first as css.LiteralTerm);
+          break;
+        case 'text-shadow':
+          style.textShadow = ExpressionMapping.expressionToTextShadow(value);
+          break;
+      }
     }
   });
   return style;
 }
 
-Style inlineCSSToStyle(String inlineStyle) {
+Style inlineCSSToStyle(String? inlineStyle) {
   final sheet = cssparser.parse("*{$inlineStyle}");
-  final declarations = DeclarationVisitor().getDeclarations(sheet);
+  final declarations = DeclarationVisitor().getDeclarations(sheet)!;
   return declarationsToStyle(declarations);
 }
 
 class DeclarationVisitor extends css.Visitor {
-  Map<String, List<css.Expression>> _result;
-  String _currentProperty;
+  Map<String?, List<css.Expression>>? _result;
+  String? _currentProperty;
 
-  Map<String, List<css.Expression>> getDeclarations(css.StyleSheet sheet) {
-    _result = new Map<String, List<css.Expression>>();
+  Map<String?, List<css.Expression>>? getDeclarations(css.StyleSheet sheet) {
+    _result = new Map<String?, List<css.Expression>>();
     sheet.visit(this);
     return _result;
   }
@@ -91,28 +98,28 @@ class DeclarationVisitor extends css.Visitor {
   @override
   void visitDeclaration(css.Declaration node) {
     _currentProperty = node.property;
-    _result[_currentProperty] = new List<css.Expression>();
-    node.expression.visit(this);
+    _result![_currentProperty] = <css.Expression>[];
+    node.expression!.visit(this);
   }
 
   @override
   void visitExpressions(css.Expressions node) {
     node.expressions.forEach((expression) {
-      _result[_currentProperty].add(expression);
+      _result![_currentProperty]!.add(expression);
     });
   }
 }
 
 //Mapping functions
 class ExpressionMapping {
-  static Color expressionToColor(css.Expression value) {
+  static Color? expressionToColor(css.Expression value) {
     if (value is css.HexColorTerm) {
       return stringToColor(value.text);
     } else if (value is css.FunctionTerm) {
       if (value.text == 'rgba') {
-        return rgbOrRgbaToColor(value.span.text);
+        return rgbOrRgbaToColor(value.span!.text);
       } else if (value.text == 'rgb') {
-        return rgbOrRgbaToColor(value.span.text);
+        return rgbOrRgbaToColor(value.span!.text);
       }
     }
     return null;
@@ -171,15 +178,15 @@ class ExpressionMapping {
     return finalFontFeatures;
   }
 
-  static FontSize expressionToFontSize(css.Expression value) {
+  static FontSize? expressionToFontSize(css.Expression value) {
     if (value is css.NumberTerm) {
       return FontSize(double.tryParse(value.text));
     } else if (value is css.PercentageTerm) {
-      return FontSize.percent(int.tryParse(value.text));
+      return FontSize.percent(int.tryParse(value.text)!);
     } else if (value is css.EmTerm) {
       return FontSize.em(double.tryParse(value.text));
     } else if (value is css.RemTerm) {
-      return FontSize.rem(double.tryParse(value.text));
+      return FontSize.rem(double.tryParse(value.text)!);
     } else if (value is css.LengthTerm) {
       return FontSize(double.tryParse(value.text.replaceAll(new RegExp(r'\s+(\d+\.\d+)\s+'), '')));
     } else if (value is css.LiteralTerm) {
@@ -251,20 +258,20 @@ class ExpressionMapping {
     return FontWeight.normal;
   }
 
-  static String expressionToFontFamily(css.Expression value) {
+  static String? expressionToFontFamily(css.Expression value) {
     if (value is css.LiteralTerm) return value.text;
     return null;
   }
 
   static LineHeight expressionToLineHeight(css.Expression value) {
     if (value is css.NumberTerm) {
-      return LineHeight.number(double.tryParse(value.text));
+      return LineHeight.number(double.tryParse(value.text)!);
     } else if (value is css.PercentageTerm) {
-      return LineHeight.percent(double.tryParse(value.text));
+      return LineHeight.percent(double.tryParse(value.text)!);
     } else if (value is css.EmTerm) {
-      return LineHeight.em(double.tryParse(value.text));
+      return LineHeight.em(double.tryParse(value.text)!);
     } else if (value is css.RemTerm) {
-      return LineHeight.rem(double.tryParse(value.text));
+      return LineHeight.rem(double.tryParse(value.text)!);
     } else if (value is css.LengthTerm) {
       return LineHeight(double.tryParse(value.text.replaceAll(new RegExp(r'\s+(\d+\.\d+)\s+'), '')), units: "length");
     }
@@ -291,22 +298,24 @@ class ExpressionMapping {
     return TextAlign.start;
   }
 
-  static TextDecoration expressionToTextDecorationLine(List<css.LiteralTerm> value) {
+  static TextDecoration expressionToTextDecorationLine(List<css.LiteralTerm?> value) {
     List<TextDecoration> decorationList = [];
-    for (css.LiteralTerm term in value) {
-      switch(term.text) {
-        case "overline":
-          decorationList.add(TextDecoration.overline);
-          break;
-        case "underline":
-          decorationList.add(TextDecoration.underline);
-          break;
-        case "line-through":
-          decorationList.add(TextDecoration.lineThrough);
-          break;
-        default:
-          decorationList.add(TextDecoration.none);
-          break;
+    for (css.LiteralTerm? term in value) {
+      if (term != null) {
+        switch(term.text) {
+          case "overline":
+            decorationList.add(TextDecoration.overline);
+            break;
+          case "underline":
+            decorationList.add(TextDecoration.underline);
+            break;
+          case "line-through":
+            decorationList.add(TextDecoration.lineThrough);
+            break;
+          default:
+            decorationList.add(TextDecoration.none);
+            break;
+        }
       }
     }
     if (decorationList.contains(TextDecoration.none)) decorationList = [TextDecoration.none];
@@ -346,31 +355,31 @@ class ExpressionMapping {
     for (List<css.Expression> list in valueList) {
       css.Expression exp = list[0];
       css.Expression exp2 = list[1];
-      css.LiteralTerm exp3 = list.length > 2 ? list[2] : null;
-      css.LiteralTerm exp4 = list.length > 3 ? list[3] : null;
+      css.LiteralTerm? exp3 = list.length > 2 ? list[2] as css.LiteralTerm? : null;
+      css.LiteralTerm? exp4 = list.length > 3 ? list[3] as css.LiteralTerm? : null;
       RegExp nonNumberRegex = RegExp(r'\s+(\d+\.\d+)\s+');
       if (exp is css.LiteralTerm && exp2 is css.LiteralTerm) {
         if (exp3 != null && (exp3 is css.HexColorTerm || exp3 is css.FunctionTerm)) {
           shadow.add(Shadow(
-              color: expressionToColor(exp3), 
-              offset: Offset(double.tryParse(exp.text.replaceAll(nonNumberRegex, '')), double.tryParse(exp2.text.replaceAll(nonNumberRegex, '')))
+              color: expressionToColor(exp3)!, 
+              offset: Offset(double.tryParse(exp.text.replaceAll(nonNumberRegex, ''))!, double.tryParse(exp2.text.replaceAll(nonNumberRegex, ''))!)
           ));
         } else if (exp3 != null && exp3 is css.LiteralTerm) {
           if (exp4 != null && (exp4 is css.HexColorTerm || exp4 is css.FunctionTerm)) {
             shadow.add(Shadow(
-                color: expressionToColor(exp4), 
-                offset: Offset(double.tryParse(exp.text.replaceAll(nonNumberRegex, '')), double.tryParse(exp2.text.replaceAll(nonNumberRegex, ''))), 
-                blurRadius: double.tryParse(exp3.text.replaceAll(nonNumberRegex, ''))
+                color: expressionToColor(exp4)!, 
+                offset: Offset(double.tryParse(exp.text.replaceAll(nonNumberRegex, ''))!, double.tryParse(exp2.text.replaceAll(nonNumberRegex, ''))!), 
+                blurRadius: double.tryParse(exp3.text.replaceAll(nonNumberRegex, ''))!
             ));
           } else {
             shadow.add(Shadow(
-                offset: Offset(double.tryParse(exp.text.replaceAll(nonNumberRegex, '')), double.tryParse(exp2.text.replaceAll(nonNumberRegex, ''))), 
-                blurRadius: double.tryParse(exp3.text.replaceAll(nonNumberRegex, ''))
+                offset: Offset(double.tryParse(exp.text.replaceAll(nonNumberRegex, ''))!, double.tryParse(exp2.text.replaceAll(nonNumberRegex, ''))!), 
+                blurRadius: double.tryParse(exp3.text.replaceAll(nonNumberRegex, ''))!
             ));
           }
         } else {
           shadow.add(Shadow(
-              offset: Offset(double.tryParse(exp.text.replaceAll(nonNumberRegex, '')), double.tryParse(exp2.text.replaceAll(nonNumberRegex, '')))
+              offset: Offset(double.tryParse(exp.text.replaceAll(nonNumberRegex, ''))!, double.tryParse(exp2.text.replaceAll(nonNumberRegex, ''))!)
           ));
         }
       }
@@ -393,7 +402,7 @@ class ExpressionMapping {
     }
   }
 
-  static Color rgbOrRgbaToColor(String text) {
+  static Color? rgbOrRgbaToColor(String text) {
     final rgbaText = text.replaceAll(')', '').replaceAll(' ', '');
     try {
       final rgbaValues =
diff --git a/lib/src/interactable_element.dart b/lib/src/interactable_element.dart
index 98bdd3df41..b3948029b1 100644
--- a/lib/src/interactable_element.dart
+++ b/lib/src/interactable_element.dart
@@ -5,15 +5,15 @@ import 'package:html/dom.dart' as dom;
 
 /// An [InteractableElement] is a [StyledElement] that takes user gestures (e.g. tap).
 class InteractableElement extends StyledElement {
-  String href;
+  String? href;
 
   InteractableElement({
-    String name,
-    List<StyledElement> children,
-    Style style,
-    this.href,
-    dom.Node node,
-  }) : super(name: name, children: children, style: style, node: node);
+    required String name,
+    required List<StyledElement> children,
+    required Style style,
+    required this.href,
+    required dom.Node node,
+  }) : super(name: name, children: children, style: style, node: node as dom.Element?);
 }
 
 /// A [Gesture] indicates the type of interaction by a user.
@@ -23,21 +23,26 @@ enum Gesture {
 
 InteractableElement parseInteractableElement(
     dom.Element element, List<StyledElement> children) {
-  InteractableElement interactableElement = InteractableElement(
-    name: element.localName,
-    children: children,
-    node: element,
-  );
-
   switch (element.localName) {
     case "a":
-      interactableElement.href = element.attributes['href'];
-      interactableElement.style = Style(
-        color: Colors.blue,
-        textDecoration: TextDecoration.underline,
+      return InteractableElement(
+        name: element.localName!,
+        children: children,
+        href: element.attributes['href'],
+        style: Style(
+          color: Colors.blue,
+          textDecoration: TextDecoration.underline,
+        ),
+        node: element,
+      );
+    /// will never be called, just to suppress missing return warning
+    default:
+      return InteractableElement(
+        name: element.localName!,
+        children: children,
+        node: element,
+        href: '',
+        style: Style(),
       );
-      break;
   }
-
-  return interactableElement;
 }
\ No newline at end of file
diff --git a/lib/src/layout_element.dart b/lib/src/layout_element.dart
index 0950b51c18..4d61b1ed01 100644
--- a/lib/src/layout_element.dart
+++ b/lib/src/layout_element.dart
@@ -12,22 +12,20 @@ import 'package:html/dom.dart' as dom;
 /// an html document with a more complex layout. LayoutElements handle
 abstract class LayoutElement extends StyledElement {
   LayoutElement({
-    String name,
-    List<StyledElement> children,
-    Style style,
-    dom.Element node,
-  }) : super(name: name, children: children, style: style, node: node);
+    String name = "[[No Name]]",
+    required List<StyledElement> children,
+    dom.Element? node,
+  }) : super(name: name, children: children, style: Style(), node: node);
 
-  Widget toWidget(RenderContext context);
+  Widget? toWidget(RenderContext context);
 }
 
 class TableLayoutElement extends LayoutElement {
   TableLayoutElement({
-    String name,
-    Style style,
-    @required List<StyledElement> children,
-    dom.Element node,
-  }) : super(name: name, style: style, children: children, node: node);
+    required String name,
+    required List<StyledElement> children,
+    required dom.Element node,
+  }) : super(name: name, children: children, node: node);
 
   @override
   Widget toWidget(RenderContext context) {
@@ -51,8 +49,7 @@ class TableLayoutElement extends LayoutElement {
         columnSizes = child.children
             .where((c) => c.name == "col")
             .map((c) {
-              final span =
-                  int.parse(c.attributes["span"] ?? "1", onError: (_) => 1);
+              final span = int.tryParse(c.attributes["span"] ?? "1") ?? 1;
               final colWidth = c.attributes["width"];
               return List.generate(span, (index) {
                 if (colWidth != null && colWidth.endsWith("%")) {
@@ -137,16 +134,15 @@ class TableLayoutElement extends LayoutElement {
     }
 
     // Create column tracks (insofar there were no colgroups that already defined them)
-    List<TrackSize> finalColumnSizes =
-        (columnSizes ?? <TrackSize>[]).take(columnMax).toList();
+    List<TrackSize> finalColumnSizes = columnSizes.take(columnMax).toList();
     finalColumnSizes += List.generate(
         max(0, columnMax - finalColumnSizes.length),
         (_) => IntrinsicContentTrackSize());
 
     return LayoutGrid(
       gridFit: GridFit.loose,
-      templateColumnSizes: finalColumnSizes,
-      templateRowSizes: rowSizes,
+      columnSizes: finalColumnSizes,
+      rowSizes: rowSizes,
       children: cells,
     );
   }
@@ -154,8 +150,8 @@ class TableLayoutElement extends LayoutElement {
 
 class TableSectionLayoutElement extends LayoutElement {
   TableSectionLayoutElement({
-    String name,
-    @required List<StyledElement> children,
+    required String name,
+    required List<StyledElement> children,
   }) : super(name: name, children: children);
 
   @override
@@ -167,9 +163,9 @@ class TableSectionLayoutElement extends LayoutElement {
 
 class TableRowLayoutElement extends LayoutElement {
   TableRowLayoutElement({
-    String name,
-    @required List<StyledElement> children,
-    dom.Element node,
+    required String name,
+    required List<StyledElement> children,
+    required dom.Element node,
   }) : super(name: name, children: children, node: node);
 
   @override
@@ -184,19 +180,13 @@ class TableCellElement extends StyledElement {
   int rowspan = 1;
 
   TableCellElement({
-    String name,
-    String elementId,
-    List<String> elementClasses,
-    @required List<StyledElement> children,
-    Style style,
-    dom.Element node,
-  }) : super(
-            name: name,
-            elementId: elementId,
-            elementClasses: elementClasses,
-            children: children,
-            style: style,
-            node: node) {
+    required String name,
+    required String elementId,
+    required List<String> elementClasses,
+    required List<StyledElement> children,
+    required Style style,
+    required dom.Element node,
+  }) : super(name: name, elementId: elementId, elementClasses: elementClasses, children: children, style: style, node: node) {
     colspan = _parseSpan(this, "colspan");
     rowspan = _parseSpan(this, "rowspan");
   }
@@ -212,11 +202,12 @@ TableCellElement parseTableCellElement(
   List<StyledElement> children,
 ) {
   final cell = TableCellElement(
-    name: element.localName,
+    name: element.localName!,
     elementId: element.id,
     elementClasses: element.classes.toList(),
     children: children,
     node: element,
+    style: Style(),
   );
   if (element.localName == "th") {
     cell.style = Style(
@@ -228,10 +219,10 @@ TableCellElement parseTableCellElement(
 
 class TableStyleElement extends StyledElement {
   TableStyleElement({
-    String name,
-    List<StyledElement> children,
-    Style style,
-    dom.Element node,
+    required String name,
+    required List<StyledElement> children,
+    required Style style,
+    required dom.Element node,
   }) : super(name: name, children: children, style: style, node: node);
 }
 
@@ -243,12 +234,18 @@ TableStyleElement parseTableDefinitionElement(
     case "colgroup":
     case "col":
       return TableStyleElement(
-        name: element.localName,
+        name: element.localName!,
         children: children,
         node: element,
+        style: Style(),
       );
     default:
-      return TableStyleElement();
+      return TableStyleElement(
+        name: "[[No Name]]",
+        children: children,
+        node: element,
+        style: Style(),
+      );
   }
 }
 
@@ -256,33 +253,31 @@ class DetailsContentElement extends LayoutElement {
   List<dom.Element> elementList;
 
   DetailsContentElement({
-    String name,
-    List<StyledElement> children,
-    dom.Element node,
-    this.elementList,
+    required String name,
+    required List<StyledElement> children,
+    required dom.Element node,
+    required this.elementList,
   }) : super(name: name, node: node, children: children);
 
   @override
   Widget toWidget(RenderContext context) {
-    List<InlineSpan> childrenList = children?.map((tree) => context.parser.parseTree(context, tree))?.toList();
+    List<InlineSpan>? childrenList = children.map((tree) => context.parser.parseTree(context, tree)).toList();
     List<InlineSpan> toRemove = [];
-    if (childrenList != null) {
-      for (InlineSpan child in childrenList) {
-        if (child is TextSpan && child.text != null && child.text.trim().isEmpty) {
-          toRemove.add(child);
-        }
-      }
-      for (InlineSpan child in toRemove) {
-        childrenList.remove(child);
+    for (InlineSpan child in childrenList) {
+      if (child is TextSpan && child.text != null && child.text!.trim().isEmpty) {
+        toRemove.add(child);
       }
     }
-    InlineSpan firstChild = childrenList?.isNotEmpty == true ? childrenList.first : null;
+    for (InlineSpan child in toRemove) {
+      childrenList.remove(child);
+    }
+    InlineSpan? firstChild = childrenList.isNotEmpty == true ? childrenList.first : null;
     return ExpansionTile(
         expandedAlignment: Alignment.centerLeft,
-        title: elementList?.isNotEmpty == true && elementList?.first?.localName == "summary" ? StyledText(
+        title: elementList.isNotEmpty == true && elementList.first.localName == "summary" ? StyledText(
           textSpan: TextSpan(
             style: style.generateTextStyle(),
-            children: [firstChild] ?? [],
+            children: firstChild == null ? [] : [firstChild],
           ),
           style: style,
           renderContext: context,
@@ -291,7 +286,7 @@ class DetailsContentElement extends LayoutElement {
           StyledText(
             textSpan: TextSpan(
               style: style.generateTextStyle(),
-              children: getChildren(childrenList, context, elementList?.isNotEmpty == true && elementList?.first?.localName == "summary" ? firstChild : null)
+              children: getChildren(childrenList, context, elementList.isNotEmpty == true && elementList.first.localName == "summary" ? firstChild : null)
             ),
             style: style,
             renderContext: context,
@@ -300,21 +295,17 @@ class DetailsContentElement extends LayoutElement {
     );
   }
 
-  List<InlineSpan> getChildren(List<InlineSpan> children, RenderContext context, InlineSpan firstChild) {
-    if (children == null) {
-      return [];
-    } else {
-      if (firstChild != null) children.removeAt(0);
-      return children;
-    }
+  List<InlineSpan> getChildren(List<InlineSpan> children, RenderContext context, InlineSpan? firstChild) {
+    if (firstChild != null) children.removeAt(0);
+    return children;
   }
 }
 
 class EmptyLayoutElement extends LayoutElement {
-  EmptyLayoutElement({String name = "empty"}) : super(name: name);
+  EmptyLayoutElement({required String name}) : super(name: name, children: []);
 
   @override
-  Widget toWidget(_) => null;
+  Widget? toWidget(_) => null;
 }
 
 LayoutElement parseLayoutElement(
@@ -323,38 +314,39 @@ LayoutElement parseLayoutElement(
 ) {
   switch (element.localName) {
     case "details":
-      if (children?.isEmpty ?? false) {
-        return EmptyLayoutElement();
+      if (children.isEmpty) {
+        return EmptyLayoutElement(name: "empty");
       }
       return DetailsContentElement(
           node: element,
-          name: element.localName,
+          name: element.localName!,
           children: children,
           elementList: element.children
       );
     case "table":
       return TableLayoutElement(
-        name: element.localName,
+        name: element.localName!,
         children: children,
         node: element,
       );
-      break;
     case "thead":
     case "tbody":
     case "tfoot":
       return TableSectionLayoutElement(
-        name: element.localName,
+        name: element.localName!,
         children: children,
       );
-      break;
     case "tr":
       return TableRowLayoutElement(
-        name: element.localName,
+        name: element.localName!,
         children: children,
         node: element,
       );
-      break;
     default:
-      return TableLayoutElement(children: children);
+      return TableLayoutElement(
+          children: children,
+          name: "[[No Name]]",
+          node: element
+      );
   }
 }
diff --git a/lib/src/replaced_element.dart b/lib/src/replaced_element.dart
index 95da181ee8..edb8420264 100644
--- a/lib/src/replaced_element.dart
+++ b/lib/src/replaced_element.dart
@@ -2,7 +2,6 @@ import 'dart:math';
 
 import 'package:chewie/chewie.dart';
 import 'package:chewie_audio/chewie_audio.dart';
-import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_html/html_parser.dart';
@@ -24,14 +23,14 @@ import 'package:webview_flutter/webview_flutter.dart';
 abstract class ReplacedElement extends StyledElement {
   PlaceholderAlignment alignment;
 
-  ReplacedElement(
-      {String name,
-      Style style,
-      dom.Element node,
-      this.alignment = PlaceholderAlignment.aboveBaseline})
-      : super(name: name, children: null, style: style, node: node);
+  ReplacedElement({
+    required String name,
+    required Style style,
+    dom.Element? node,
+    this.alignment = PlaceholderAlignment.aboveBaseline
+  }) : super(name: name, children: [], style: style, node: node);
 
-  static List<String> parseMediaSources(List<dom.Element> elements) {
+  static List<String?> parseMediaSources(List<dom.Element> elements) {
     return elements
         .where((element) => element.localName == 'source')
         .map((element) {
@@ -39,63 +38,55 @@ abstract class ReplacedElement extends StyledElement {
     }).toList();
   }
 
-  Widget toWidget(RenderContext context);
+  Widget? toWidget(RenderContext context);
 }
 
 /// [TextContentElement] is a [ContentElement] with plaintext as its content.
 class TextContentElement extends ReplacedElement {
-  String text;
+  String? text;
 
   TextContentElement({
-    Style style,
-    this.text,
+    required Style style,
+    required this.text,
   }) : super(name: "[text]", style: style);
 
   @override
   String toString() {
-    return "\"${text.replaceAll("\n", "\\n")}\"";
+    return "\"${text!.replaceAll("\n", "\\n")}\"";
   }
 
   @override
-  Widget toWidget(_) => null;
+  Widget? toWidget(_) => null;
 }
 
 /// [ImageContentElement] is a [ReplacedElement] with an image as its content.
 /// https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img
 class ImageContentElement extends ReplacedElement {
-  final String src;
-  final String alt;
+  final String? src;
+  final String? alt;
 
   ImageContentElement({
-    String name,
-    Style style,
-    this.src,
-    this.alt,
-    dom.Element node,
-  }) : super(
-          name: name,
-          style: style,
-          node: node,
-          alignment: PlaceholderAlignment.middle,
-        );
+    required String name,
+    required this.src,
+    required this.alt,
+    required dom.Element node,
+  }) : super(name: name, style: Style(), node: node, alignment: PlaceholderAlignment.middle);
 
   @override
   Widget toWidget(RenderContext context) {
     for (final entry in context.parser.imageRenders.entries) {
       if (entry.key.call(attributes, element)) {
         final widget = entry.value.call(context, attributes, element);
-        if (widget != null) {
-          return RawGestureDetector(
-            child: widget,
-            gestures: {
-              MultipleTapGestureRecognizer: GestureRecognizerFactoryWithHandlers<MultipleTapGestureRecognizer>(
-                    () => MultipleTapGestureRecognizer(), (instance) {
-                  instance..onTap = () => context.parser.onImageTap?.call(src, context, attributes, element);
-                },
-              ),
-            },
-          );
-        }
+        return RawGestureDetector(
+          child: widget,
+          gestures: {
+            MultipleTapGestureRecognizer: GestureRecognizerFactoryWithHandlers<MultipleTapGestureRecognizer>(
+                  () => MultipleTapGestureRecognizer(), (instance) {
+                instance..onTap = () => context.parser.onImageTap?.call(src, context, attributes, element);
+              },
+            ),
+          },
+        );
       }
     }
     return SizedBox(width: 0, height: 0);
@@ -104,27 +95,28 @@ class ImageContentElement extends ReplacedElement {
 
 /// [AudioContentElement] is a [ContentElement] with an audio file as its content.
 class AudioContentElement extends ReplacedElement {
-  final List<String> src;
+  final List<String?> src;
   final bool showControls;
   final bool autoplay;
   final bool loop;
   final bool muted;
 
   AudioContentElement({
-    String name,
-    Style style,
-    this.src,
-    this.showControls,
-    this.autoplay,
-    this.loop,
-    this.muted,
-    dom.Element node,
-  }) : super(name: name, style: style, node: node);
+    required String name,
+    required this.src,
+    required this.showControls,
+    required this.autoplay,
+    required this.loop,
+    required this.muted,
+    required dom.Element node,
+  }) : super(name: name, style: Style(), node: node);
 
   @override
   Widget toWidget(RenderContext context) {
     return Container(
       width: context.style.width ?? 300,
+      height: Theme.of(context.buildContext).platform == TargetPlatform.android
+          ? 48 : 75,
       child: ChewieAudio(
         controller: ChewieAudioController(
           videoPlayerController: VideoPlayerController.network(
@@ -142,28 +134,27 @@ class AudioContentElement extends ReplacedElement {
 
 /// [VideoContentElement] is a [ContentElement] with a video file as its content.
 class VideoContentElement extends ReplacedElement {
-  final List<String> src;
-  final String poster;
+  final List<String?> src;
+  final String? poster;
   final bool showControls;
   final bool autoplay;
   final bool loop;
   final bool muted;
-  final double width;
-  final double height;
+  final double? width;
+  final double? height;
 
   VideoContentElement({
-    String name,
-    Style style,
-    this.src,
-    this.poster,
-    this.showControls,
-    this.autoplay,
-    this.loop,
-    this.muted,
-    this.width,
-    this.height,
-    dom.Element node,
-  }) : super(name: name, style: style, node: node);
+    required String name,
+    required this.src,
+    required this.poster,
+    required this.showControls,
+    required this.autoplay,
+    required this.loop,
+    required this.muted,
+    required this.width,
+    required this.height,
+    required dom.Element node,
+  }) : super(name: name, style: Style(), node: node);
 
   @override
   Widget toWidget(RenderContext context) {
@@ -178,7 +169,7 @@ class VideoContentElement extends ReplacedElement {
               src.first ?? "",
             ),
             placeholder: poster != null
-                ? Image.network(poster)
+                ? Image.network(poster!)
                 : Container(color: Colors.black),
             autoPlay: autoplay,
             looping: loop,
@@ -195,14 +186,16 @@ class VideoContentElement extends ReplacedElement {
 /// [SvgContentElement] is a [ReplacedElement] with an SVG as its contents.
 class SvgContentElement extends ReplacedElement {
   final String data;
-  final double width;
-  final double height;
+  final double? width;
+  final double? height;
 
   SvgContentElement({
-    this.data,
-    this.width,
-    this.height,
-  });
+    required String name,
+    required this.data,
+    required this.width,
+    required this.height,
+    required dom.Node node,
+  }) : super(name: name, style: Style(), node: node as dom.Element?);
 
   @override
   Widget toWidget(RenderContext context) {
@@ -215,24 +208,24 @@ class SvgContentElement extends ReplacedElement {
 }
 
 class EmptyContentElement extends ReplacedElement {
-  EmptyContentElement({String name = "empty"}) : super(name: name);
+  EmptyContentElement({String name = "empty"}) : super(name: name, style: Style());
 
   @override
-  Widget toWidget(_) => null;
+  Widget? toWidget(_) => null;
 }
 
 class RubyElement extends ReplacedElement {
   dom.Element element;
 
-  RubyElement({@required this.element, String name = "ruby"})
-      : super(name: name, alignment: PlaceholderAlignment.middle);
+  RubyElement({required this.element, String name = "ruby"})
+      : super(name: name, alignment: PlaceholderAlignment.middle, style: Style());
 
   @override
   Widget toWidget(RenderContext context) {
-    dom.Node textNode;
-    List<Widget> widgets = List<Widget>();
+    dom.Node? textNode;
+    List<Widget> widgets = <Widget>[];
     //TODO calculate based off of parent font size.
-    final rubySize = max(9.0, context.style.fontSize.size / 2);
+    final rubySize = max(9.0, context.style.fontSize!.size! / 2);
     final rubyYPos = rubySize + rubySize / 2;
     element.nodes.forEach((c) {
       if (c.nodeType == dom.Node.TEXT_NODE) {
@@ -254,7 +247,7 @@ class RubyElement extends ReplacedElement {
                                   .generateTextStyle()
                                   .copyWith(fontSize: rubySize))))),
               Container(
-                  child: Text(textNode.text.trim(),
+                  child: Text(textNode!.text!.trim(),
                       style: context.style.generateTextStyle())),
             ],
           );
@@ -273,15 +266,15 @@ class RubyElement extends ReplacedElement {
 
 ReplacedElement parseReplacedElement(
   dom.Element element,
-  NavigationDelegate navigationDelegateForIframe,
+  NavigationDelegate? navigationDelegateForIframe,
 ) {
   switch (element.localName) {
     case "audio":
-      final sources = <String>[
+      final sources = <String?>[
         if (element.attributes['src'] != null) element.attributes['src'],
         ...ReplacedElement.parseMediaSources(element.children),
       ];
-      if (sources == null || sources.isEmpty || sources.first == null) {
+      if (sources.isEmpty || sources.first == null) {
         return EmptyContentElement();
       }
       return AudioContentElement(
@@ -305,7 +298,8 @@ ReplacedElement parseReplacedElement(
           width: double.tryParse(element.attributes['width'] ?? ""),
           height: double.tryParse(element.attributes['height'] ?? ""),
           navigationDelegate: navigationDelegateForIframe,
-          node: element);
+          node: element,
+      );
     case "img":
       return ImageContentElement(
         name: "img",
@@ -314,11 +308,11 @@ ReplacedElement parseReplacedElement(
         node: element,
       );
     case "video":
-      final sources = <String>[
+      final sources = <String?>[
         if (element.attributes['src'] != null) element.attributes['src'],
         ...ReplacedElement.parseMediaSources(element.children),
       ];
-      if (sources == null || sources.isEmpty || sources.first == null) {
+      if (sources.isEmpty || sources.first == null) {
         return EmptyContentElement();
       }
       return VideoContentElement(
@@ -335,15 +329,17 @@ ReplacedElement parseReplacedElement(
       );
     case "svg":
       return SvgContentElement(
+        name: "svg",
         data: element.outerHtml,
         width: double.tryParse(element.attributes['width'] ?? ""),
         height: double.tryParse(element.attributes['height'] ?? ""),
+        node: element,
       );
     case "ruby":
       return RubyElement(
         element: element,
       );
     default:
-      return EmptyContentElement(name: element.localName);
+      return EmptyContentElement(name: element.localName == null ? "[[No Name]]" : element.localName!);
   }
 }
diff --git a/lib/src/styled_element.dart b/lib/src/styled_element.dart
index 1d9ffb970e..6d80f9db80 100644
--- a/lib/src/styled_element.dart
+++ b/lib/src/styled_element.dart
@@ -11,33 +11,33 @@ class StyledElement {
   final List<String> elementClasses;
   List<StyledElement> children;
   Style style;
-  final dom.Node _node;
+  final dom.Node? _node;
 
   StyledElement({
     this.name = "[[No name]]",
-    this.elementId,
-    this.elementClasses,
-    this.children,
-    this.style,
-    dom.Element node,
+    this.elementId = "[[No ID]]",
+    this.elementClasses = const [],
+    required this.children,
+    required this.style,
+    required dom.Element? node,
   }) : this._node = node;
 
   bool matchesSelector(String selector) =>
-      _node != null && matches(_node, selector);
+      _node != null && matches(_node as dom.Element, selector);
 
   Map<String, String> get attributes =>
-      _node?.attributes?.map((key, value) {
-        return MapEntry(key, value);
+      _node?.attributes.map((key, value) {
+        return MapEntry(key.toString(), value);
       }) ??
       Map<String, String>();
 
-  dom.Element get element => _node;
+  dom.Element? get element => _node as dom.Element?;
 
   @override
   String toString() {
     String selfData =
-        "[$name] ${children?.length ?? 0} ${elementClasses?.isNotEmpty == true ? 'C:${elementClasses.toString()}' : ''}${elementId?.isNotEmpty == true ? 'ID: $elementId' : ''}";
-    children?.forEach((child) {
+        "[$name] ${children.length} ${elementClasses.isNotEmpty == true ? 'C:${elementClasses.toString()}' : ''}${elementId.isNotEmpty == true ? 'ID: $elementId' : ''}";
+    children.forEach((child) {
       selfData += ("\n${child.toString()}")
           .replaceAll(RegExp("^", multiLine: true), "-");
     });
@@ -48,11 +48,12 @@ class StyledElement {
 StyledElement parseStyledElement(
     dom.Element element, List<StyledElement> children) {
   StyledElement styledElement = StyledElement(
-    name: element.localName,
+    name: element.localName!,
     elementId: element.id,
     elementClasses: element.classes.toList(),
     children: children,
     node: element,
+    style: Style(),
   );
 
   switch (element.localName) {
@@ -97,7 +98,7 @@ StyledElement parseStyledElement(
       break;
     case "blockquote":
       //TODO(Sub6Resources) this is a workaround for collapsing margins. Remove.
-      if (element.parent.localName == "blockquote") {
+      if (element.parent!.localName == "blockquote") {
         styledElement.style = Style(
           margin: const EdgeInsets.only(left: 40.0, right: 40.0, bottom: 14.0),
           display: Display.BLOCK,
@@ -283,7 +284,7 @@ StyledElement parseStyledElement(
     case "ol":
     case "ul":
       //TODO(Sub6Resources): This is a workaround for collapsed margins. Remove.
-      if (element.parent.localName == "li") {
+      if (element.parent!.localName == "li") {
         styledElement.style = Style(
 //          margin: EdgeInsets.only(left: 30.0),
           display: Display.BLOCK,
diff --git a/lib/src/widgets/iframe_mobile.dart b/lib/src/widgets/iframe_mobile.dart
index 13a67513d9..bd9c7e02c8 100644
--- a/lib/src/widgets/iframe_mobile.dart
+++ b/lib/src/widgets/iframe_mobile.dart
@@ -9,21 +9,20 @@ import 'package:html/dom.dart' as dom;
 
 /// [IframeContentElement is a [ReplacedElement] with web content.
 class IframeContentElement extends ReplacedElement {
-  final String src;
-  final double width;
-  final double height;
-  final NavigationDelegate navigationDelegate;
+  final String? src;
+  final double? width;
+  final double? height;
+  final NavigationDelegate? navigationDelegate;
   final UniqueKey key = UniqueKey();
 
   IframeContentElement({
-    String name,
-    Style style,
-    this.src,
-    this.width,
-    this.height,
-    dom.Element node,
-    this.navigationDelegate,
-  }) : super(name: name, style: style, node: node);
+    required String name,
+    required this.src,
+    required this.width,
+    required this.height,
+    required dom.Element node,
+    required this.navigationDelegate,
+  }) : super(name: name, style: Style(), node: node);
 
   @override
   Widget toWidget(RenderContext context) {
diff --git a/lib/src/widgets/iframe_unsupported.dart b/lib/src/widgets/iframe_unsupported.dart
index 35c72d2388..f7a74fde3e 100644
--- a/lib/src/widgets/iframe_unsupported.dart
+++ b/lib/src/widgets/iframe_unsupported.dart
@@ -7,21 +7,20 @@ import 'package:html/dom.dart' as dom;
 
 /// [IframeContentElement is a [ReplacedElement] with web content.
 class IframeContentElement extends ReplacedElement {
-  final String src;
-  final double width;
-  final double height;
-  final NavigationDelegate navigationDelegate;
+  final String? src;
+  final double? width;
+  final double? height;
+  final NavigationDelegate? navigationDelegate;
   final UniqueKey key = UniqueKey();
 
   IframeContentElement({
-    String name,
-    Style style,
-    this.src,
-    this.width,
-    this.height,
-    dom.Element node,
-    this.navigationDelegate,
-  }) : super(name: name, style: style, node: node);
+    required String name,
+    required this.src,
+    required this.width,
+    required this.height,
+    required dom.Element node,
+    required this.navigationDelegate,
+  }) : super(name: name, style: Style(), node: node);
 
   @override
   Widget toWidget(RenderContext context) {
diff --git a/lib/src/widgets/iframe_web.dart b/lib/src/widgets/iframe_web.dart
index 59eb8ee892..1a9c348461 100644
--- a/lib/src/widgets/iframe_web.dart
+++ b/lib/src/widgets/iframe_web.dart
@@ -11,22 +11,21 @@ import 'dart:ui' as ui;
 
 /// [IframeContentElement is a [ReplacedElement] with web content.
 class IframeContentElement extends ReplacedElement {
-  final String src;
-  final double width;
-  final double height;
-  final NavigationDelegate navigationDelegate;
+  final String? src;
+  final double? width;
+  final double? height;
+  final NavigationDelegate? navigationDelegate;
   final UniqueKey key = UniqueKey();
   final String createdViewId = getRandString(10);
 
   IframeContentElement({
-    String name,
-    Style style,
-    this.src,
-    this.width,
-    this.height,
-    dom.Element node,
-    this.navigationDelegate,
-  }) : super(name: name, style: style, node: node);
+    required String name,
+    required this.src,
+    required this.width,
+    required this.height,
+    required dom.Element node,
+    required this.navigationDelegate,
+  }) : super(name: name, style: Style(), node: node);
 
   @override
   Widget toWidget(RenderContext context) {
diff --git a/lib/style.dart b/lib/style.dart
index 65eb39469e..2f889cc477 100644
--- a/lib/style.dart
+++ b/lib/style.dart
@@ -9,115 +9,115 @@ class Style {
   ///
   /// Inherited: no,
   /// Default: Colors.transparent,
-  Color backgroundColor;
+  Color? backgroundColor;
 
   /// CSS attribute "`color`"
   ///
   /// Inherited: yes,
   /// Default: unspecified,
-  Color color;
+  Color? color;
 
   /// CSS attribute "`direction`"
   ///
   /// Inherited: yes,
   /// Default: TextDirection.ltr,
-  TextDirection direction;
+  TextDirection? direction;
 
   /// CSS attribute "`display`"
   ///
   /// Inherited: no,
   /// Default: unspecified,
-  Display display;
+  Display? display;
 
   /// CSS attribute "`font-family`"
   ///
   /// Inherited: yes,
   /// Default: Theme.of(context).style.textTheme.body1.fontFamily
-  String fontFamily;
+  String? fontFamily;
 
   /// CSS attribute "`font-feature-settings`"
   ///
   /// Inherited: yes,
   /// Default: normal
-  List<FontFeature> fontFeatureSettings;
+  List<FontFeature>? fontFeatureSettings;
 
   /// CSS attribute "`font-size`"
   ///
   /// Inherited: yes,
   /// Default: FontSize.medium
-  FontSize fontSize;
+  FontSize? fontSize;
 
   /// CSS attribute "`font-style`"
   ///
   /// Inherited: yes,
   /// Default: FontStyle.normal,
-  FontStyle fontStyle;
+  FontStyle? fontStyle;
 
   /// CSS attribute "`font-weight`"
   ///
   /// Inherited: yes,
   /// Default: FontWeight.normal,
-  FontWeight fontWeight;
+  FontWeight? fontWeight;
 
   /// CSS attribute "`height`"
   ///
   /// Inherited: no,
   /// Default: Unspecified (null),
-  double height;
+  double? height;
 
   /// CSS attribute "`letter-spacing`"
   ///
   /// Inherited: yes,
   /// Default: normal (0),
-  double letterSpacing;
+  double? letterSpacing;
 
   /// CSS attribute "`list-style-type`"
   ///
   /// Inherited: yes,
   /// Default: ListStyleType.DISC
-  ListStyleType listStyleType;
+  ListStyleType? listStyleType;
 
   /// CSS attribute "`list-style-position`"
   ///
   /// Inherited: yes,
   /// Default: ListStylePosition.OUTSIDE
-  ListStylePosition listStylePosition;
+  ListStylePosition? listStylePosition;
 
   /// CSS attribute "`padding`"
   ///
   /// Inherited: no,
   /// Default: EdgeInsets.zero
-  EdgeInsets padding;
+  EdgeInsets? padding;
 
   /// CSS attribute "`margin`"
   ///
   /// Inherited: no,
   /// Default: EdgeInsets.zero
-  EdgeInsets margin;
+  EdgeInsets? margin;
 
   /// CSS attribute "`text-align`"
   ///
   /// Inherited: yes,
   /// Default: TextAlign.start,
-  TextAlign textAlign;
+  TextAlign? textAlign;
 
   /// CSS attribute "`text-decoration`"
   ///
   /// Inherited: no,
   /// Default: TextDecoration.none,
-  TextDecoration textDecoration;
+  TextDecoration? textDecoration;
 
   /// CSS attribute "`text-decoration-color`"
   ///
   /// Inherited: no,
   /// Default: Current color
-  Color textDecorationColor;
+  Color? textDecorationColor;
 
   /// CSS attribute "`text-decoration-style`"
   ///
   /// Inherited: no,
   /// Default: TextDecorationStyle.solid,
-  TextDecorationStyle textDecorationStyle;
+  TextDecorationStyle? textDecorationStyle;
 
   /// Loosely based on CSS attribute "`text-decoration-thickness`"
   ///
@@ -126,37 +126,37 @@ class Style {
   /// Inherited: no,
   /// Default: 1.0 (specified by font size)
   // TODO(Sub6Resources): Possibly base this more closely on the CSS attribute.
-  double textDecorationThickness;
+  double? textDecorationThickness;
 
   /// CSS attribute "`text-shadow`"
   ///
   /// Inherited: yes,
   /// Default: none,
-  List<Shadow> textShadow;
+  List<Shadow>? textShadow;
 
   /// CSS attribute "`vertical-align`"
   ///
   /// Inherited: no,
   /// Default: VerticalAlign.BASELINE,
-  VerticalAlign verticalAlign;
+  VerticalAlign? verticalAlign;
 
   /// CSS attribute "`white-space`"
   ///
   /// Inherited: yes,
   /// Default: WhiteSpace.NORMAL,
-  WhiteSpace whiteSpace;
+  WhiteSpace? whiteSpace;
 
   /// CSS attribute "`width`"
   ///
   /// Inherited: no,
   /// Default: unspecified (null)
-  double width;
+  double? width;
 
   /// CSS attribute "`word-spacing`"
   ///
   /// Inherited: yes,
   /// Default: normal (0)
-  double wordSpacing;
+  double? wordSpacing;
 
   /// CSS attribute "`line-height`"
   ///
@@ -166,14 +166,14 @@ class Style {
   ///
   /// Inherited: no,
   /// Default: Unspecified (null),
-  LineHeight lineHeight;
+  LineHeight? lineHeight;
 
   //TODO modify these to match CSS styles
-  String before;
-  String after;
-  Border border;
-  Alignment alignment;
-  String markerContent;
+  String? before;
+  String? after;
+  Border? border;
+  Alignment? alignment;
+  String? markerContent;
 
   Style({
     this.backgroundColor = Colors.transparent,
@@ -242,8 +242,6 @@ class Style {
   }
 
   Style merge(Style other) {
-    if (other == null) return this;
-
     return copyWith(
       backgroundColor: other.backgroundColor,
       color: other.color,
@@ -284,16 +282,14 @@ class Style {
   }
 
   Style copyOnlyInherited(Style child) {
-    if (child == null) return this;
-
-    FontSize finalFontSize = child.fontSize != null ?
+    FontSize? finalFontSize = child.fontSize != null ?
       fontSize != null && child.fontSize?.units == "em" ?
-        FontSize(child.fontSize.size * fontSize.size) : child.fontSize
-      : fontSize != null && fontSize.size < 0 ?
+        FontSize(child.fontSize!.size! * fontSize!.size!) : child.fontSize
+      : fontSize != null && fontSize!.size! < 0 ?
         FontSize.percent(100) : fontSize;
-    LineHeight finalLineHeight = child.lineHeight != null ?
+    LineHeight? finalLineHeight = child.lineHeight != null ?
       child.lineHeight?.units == "length" ?
-        LineHeight(child.lineHeight.size / (finalFontSize == null ? 14 : finalFontSize.size) * 1.2) : child.lineHeight
+        LineHeight(child.lineHeight!.size! / (finalFontSize == null ? 14 : finalFontSize.size!) * 1.2) : child.lineHeight
       : lineHeight;
     return child.copyWith(
       color: child.color ?? color,
@@ -316,37 +312,37 @@ class Style {
   }
 
   Style copyWith({
-    Color backgroundColor,
-    Color color,
-    TextDirection direction,
-    Display display,
-    String fontFamily,
-    List<FontFeature> fontFeatureSettings,
-    FontSize fontSize,
-    FontStyle fontStyle,
-    FontWeight fontWeight,
-    double height,
-    LineHeight lineHeight,
-    double letterSpacing,
-    ListStyleType listStyleType,
-    ListStylePosition listStylePosition,
-    EdgeInsets padding,
-    EdgeInsets margin,
-    TextAlign textAlign,
-    TextDecoration textDecoration,
-    Color textDecorationColor,
-    TextDecorationStyle textDecorationStyle,
-    double textDecorationThickness,
-    List<Shadow> textShadow,
-    VerticalAlign verticalAlign,
-    WhiteSpace whiteSpace,
-    double width,
-    double wordSpacing,
-    String before,
-    String after,
-    Border border,
-    Alignment alignment,
-    String markerContent,
+    Color? backgroundColor,
+    Color? color,
+    TextDirection? direction,
+    Display? display,
+    String? fontFamily,
+    List<FontFeature>? fontFeatureSettings,
+    FontSize? fontSize,
+    FontStyle? fontStyle,
+    FontWeight? fontWeight,
+    double? height,
+    LineHeight? lineHeight,
+    double? letterSpacing,
+    ListStyleType? listStyleType,
+    ListStylePosition? listStylePosition,
+    EdgeInsets? padding,
+    EdgeInsets? margin,
+    TextAlign? textAlign,
+    TextDecoration? textDecoration,
+    Color? textDecorationColor,
+    TextDecorationStyle? textDecorationStyle,
+    double? textDecorationThickness,
+    List<Shadow>? textShadow,
+    VerticalAlign? verticalAlign,
+    WhiteSpace? whiteSpace,
+    double? width,
+    double? wordSpacing,
+    String? before,
+    String? after,
+    Border? border,
+    Alignment? alignment,
+    String? markerContent,
   }) {
     return Style(
       backgroundColor: backgroundColor ?? this.backgroundColor,
@@ -412,7 +408,7 @@ enum Display {
 }
 
 class FontSize {
-  final double size;
+  final double? size;
   final String units;
 
   const FontSize(this.size, {this.units = ""});
@@ -422,7 +418,7 @@ class FontSize {
     return FontSize(percent.toDouble() / -100.0, units: "%");
   }
 
-  factory FontSize.em(double em) {
+  factory FontSize.em(double? em) {
     return FontSize(em, units: "em");
   }
 
@@ -448,7 +444,7 @@ class FontSize {
 }
 
 class LineHeight {
-  final double size;
+  final double? size;
   final String units;
 
   const LineHeight(this.size, {this.units = ""});
diff --git a/pubspec.yaml b/pubspec.yaml
index f41b5669e6..93f9779472 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,35 +1,35 @@
 name: flutter_html
 description: A Flutter widget rendering static HTML and CSS as Flutter widgets.
-version: 1.3.0
+version: 2.0.0-nullsafety.0
 homepage: https://github.com/Sub6Resources/flutter_html
 
 environment:
-  sdk: '>=2.2.2 <3.0.0'
+  sdk: '>=2.12.0 <3.0.0'
   flutter: '>=1.17.0'
 
 dependencies:
   # Plugin for parsing html
-  html: ^0.14.0+4
+  html: ^0.15.0
 
   # Plugins for parsing css
-  csslib: ^0.16.2
-  css_colors: ^1.0.2
+  csslib: ^0.17.0
+  css_colors: ^1.1.0
 
   # Plugins for rendering the <table> tag.
-  flutter_layout_grid: ^0.10.5
+  flutter_layout_grid: ^1.0.0-nullsafety.6
 
   # Plugins for rendering the <video> tag.
-  video_player: ^1.0.1
-  chewie: ^0.12.2
+  video_player: ^2.0.0
+  chewie: ^1.0.0
 
   # Plugin for rendering the <iframe> tag.
-  webview_flutter: ^1.0.7
+  webview_flutter: ^2.0.1
 
   # Plugins for rendering the <audio> tag.
-  chewie_audio: ^1.1.2
+  chewie_audio: ^1.2.0
 
   # Plugins for rendering the <svg> tag.
-  flutter_svg: ^0.20.0-nullsafety.3
+  flutter_svg: ^0.21.0-nullsafety.0
 
   flutter:
     sdk: flutter
diff --git a/test/golden_test.dart b/test/golden_test.dart
index e381b3cda1..72fc12699b 100644
--- a/test/golden_test.dart
+++ b/test/golden_test.dart
@@ -1,5 +1,3 @@
-import 'dart:io';
-
 import 'package:flutter/material.dart';
 import 'package:flutter_html/flutter_html.dart';
 import 'package:flutter_test/flutter_test.dart';
diff --git a/test/image_render_source_matcher_test.dart b/test/image_render_source_matcher_test.dart
index 6c900ea49e..49823594f9 100644
--- a/test/image_render_source_matcher_test.dart
+++ b/test/image_render_source_matcher_test.dart
@@ -117,13 +117,13 @@ void main() {
   });
 }
 
-dom.Element _fakeElement(String src) {
+dom.Element _fakeElement(String? src) {
   return dom.Element.html("""
       <img src="$src" />
     """);
 }
 
-bool _match(ImageSourceMatcher matcher, String src) {
+bool _match(ImageSourceMatcher matcher, String? src) {
   final element = _fakeElement(src);
   return matcher.call(
       element.attributes.map((key, value) => MapEntry(key.toString(), value)),