diff --git a/packages/base/src/RenderScheduler.js b/packages/base/src/RenderScheduler.js
index 964d32af4cdf..65b0ad02298c 100644
--- a/packages/base/src/RenderScheduler.js
+++ b/packages/base/src/RenderScheduler.js
@@ -142,18 +142,21 @@ class RenderScheduler {
 	 *
 	 * Usage:
 	 * reRenderAllUI5Elements() -> rerenders all components
+	 * reRenderAllUI5Elements({tag: "ui5-button"}) -> re-renders only instances of ui5-button
 	 * reRenderAllUI5Elements({rtlAware: true}) -> re-renders only rtlAware components
 	 * reRenderAllUI5Elements({languageAware: true}) -> re-renders only languageAware components
 	 * reRenderAllUI5Elements({rtlAware: true, languageAware: true}) -> re-renders components that are rtlAware or languageAware
+	 * etc...
 	 *
 	 * @public
 	 * @param {Object|undefined} filters - Object with keys that can be "rtlAware" or "languageAware"
 	 */
 	static reRenderAllUI5Elements(filters) {
 		registeredElements.forEach(element => {
+			const tag = element.constructor.getMetadata().getTag();
 			const rtlAware = isRtlAware(element.constructor);
 			const languageAware = element.constructor.getMetadata().isLanguageAware();
-			if (!filters || (filters.rtlAware && rtlAware) || (filters.languageAware && languageAware)) {
+			if (!filters || (filters.tag === tag) || (filters.rtlAware && rtlAware) || (filters.languageAware && languageAware)) {
 				RenderScheduler.renderDeferred(element);
 			}
 		});
diff --git a/packages/base/src/UI5Element.js b/packages/base/src/UI5Element.js
index 0fba1339763e..855800463b54 100644
--- a/packages/base/src/UI5Element.js
+++ b/packages/base/src/UI5Element.js
@@ -85,17 +85,6 @@ class UI5Element extends HTMLElement {
 		// Init Shadow Root
 		if (needsShadowDOM) {
 			this.attachShadow({ mode: "open" });
-
-			// IE11, Edge
-			if (window.ShadyDOM) {
-				createComponentStyleTag(this.constructor);
-			}
-
-			// Chrome
-			if (document.adoptedStyleSheets) {
-				const style = getConstructableStyle(this.constructor);
-				this.shadowRoot.adoptedStyleSheets = [style];
-			}
 		}
 
 		// Init StaticAreaItem only if needed
@@ -562,9 +551,21 @@ class UI5Element extends HTMLElement {
 		let styleToPrepend;
 		const renderResult = this.constructor.template(this);
 
+		// IE11, Edge
+		if (window.ShadyDOM) {
+			createComponentStyleTag(this.constructor);
+		}
+
+		// Chrome
+		if (document.adoptedStyleSheets) {
+			this.shadowRoot.adoptedStyleSheets = getConstructableStyle(this.constructor);
+		}
+
+		// FF, Safari
 		if (!document.adoptedStyleSheets && !window.ShadyDOM) {
 			styleToPrepend = getEffectiveStyle(this.constructor);
 		}
+
 		this.constructor.render(renderResult, this.shadowRoot, styleToPrepend, { eventContext: this });
 	}
 
diff --git a/packages/base/src/theming/CustomStyle.js b/packages/base/src/theming/CustomStyle.js
index 2632f5592b45..f3bec1874743 100644
--- a/packages/base/src/theming/CustomStyle.js
+++ b/packages/base/src/theming/CustomStyle.js
@@ -1,19 +1,40 @@
-const customCSSFor = {};
+import RenderScheduler from "../RenderScheduler.js";
+import EventProvider from "../EventProvider.js";
 
-const addCustomCSS = (tag, css, ...rest) => {
-	if (rest.length) {
-		throw new Error("addCustomCSS no longer accepts theme specific CSS. new signature is `addCustomCSS(tag, css)`");
-	}
+const eventProvider = new EventProvider();
+const CUSTOM_CSS_CHANGE = "CustomCSSChange";
+
+const attachCustomCSSChange = listener => {
+	eventProvider.attachEvent(CUSTOM_CSS_CHANGE, listener);
+};
 
+const detachCustomCSSChange = listener => {
+	eventProvider.detachEvent(CUSTOM_CSS_CHANGE, listener);
+};
+
+const fireCustomCSSChange = tag => {
+	return eventProvider.fireEvent(CUSTOM_CSS_CHANGE, tag);
+};
+
+const customCSSFor = {};
+
+const addCustomCSS = (tag, css) => {
 	if (!customCSSFor[tag]) {
 		customCSSFor[tag] = [];
 	}
-
 	customCSSFor[tag].push(css);
+	fireCustomCSSChange(tag);
+
+	RenderScheduler.reRenderAllUI5Elements({ tag });
 };
 
 const getCustomCSS = tag => {
 	return customCSSFor[tag] ? customCSSFor[tag].join("") : "";
 };
 
-export { addCustomCSS, getCustomCSS };
+export {
+	addCustomCSS,
+	getCustomCSS,
+	attachCustomCSSChange,
+	detachCustomCSSChange,
+};
diff --git a/packages/base/src/theming/createComponentStyleTag.js b/packages/base/src/theming/createComponentStyleTag.js
index 30d1eb400bb9..3267d871d70d 100644
--- a/packages/base/src/theming/createComponentStyleTag.js
+++ b/packages/base/src/theming/createComponentStyleTag.js
@@ -2,9 +2,14 @@ import createStyleInHead from "../util/createStyleInHead.js";
 import getEffectiveStyle from "./getEffectiveStyle.js";
 import adaptCSSForIE from "./adaptCSSForIE.js";
 import { ponyfillNeeded, schedulePonyfill } from "./CSSVarsPonyfill.js";
+import { attachCustomCSSChange } from "./CustomStyle.js";
 
 const IEStyleSet = new Set();
 
+attachCustomCSSChange(tag => {
+	IEStyleSet.delete(tag);
+});
+
 const getStaticStyle = ElementClass => {
 	let componentStaticStyles = ElementClass.staticAreaStyles;
 	if (Array.isArray(componentStaticStyles)) {
diff --git a/packages/base/src/theming/getConstructableStyle.js b/packages/base/src/theming/getConstructableStyle.js
index 8e65ce67e83f..ce86eedeb033 100644
--- a/packages/base/src/theming/getConstructableStyle.js
+++ b/packages/base/src/theming/getConstructableStyle.js
@@ -1,7 +1,12 @@
 import getEffectiveStyle from "./getEffectiveStyle.js";
+import { attachCustomCSSChange } from "./CustomStyle.js";
 
 const constructableStyleMap = new Map();
 
+attachCustomCSSChange(tag => {
+	constructableStyleMap.delete(tag);
+});
+
 /**
  * Returns (and caches) a constructable style sheet for a web component class
  * Note: Chrome
@@ -9,17 +14,16 @@ const constructableStyleMap = new Map();
  * @returns {*}
  */
 const getConstructableStyle = ElementClass => {
-	const tagName = ElementClass.getMetadata().getTag();
-	const styleContent = getEffectiveStyle(ElementClass);
-	if (constructableStyleMap.has(tagName)) {
-		return constructableStyleMap.get(tagName);
-	}
+	const tag = ElementClass.getMetadata().getTag();
 
-	const style = new CSSStyleSheet();
-	style.replaceSync(styleContent);
+	if (!constructableStyleMap.has(tag)) {
+		const styleContent = getEffectiveStyle(ElementClass);
+		const style = new CSSStyleSheet();
+		style.replaceSync(styleContent);
+		constructableStyleMap.set(tag, [style]);
+	}
 
-	constructableStyleMap.set(tagName, style);
-	return style;
+	return constructableStyleMap.get(tag);
 };
 
 export default getConstructableStyle;
diff --git a/packages/base/src/theming/getEffectiveStyle.js b/packages/base/src/theming/getEffectiveStyle.js
index 69a3a2d34eb1..9f40f329451f 100644
--- a/packages/base/src/theming/getEffectiveStyle.js
+++ b/packages/base/src/theming/getEffectiveStyle.js
@@ -1,12 +1,23 @@
-import { getCustomCSS } from "./CustomStyle.js";
+import { getCustomCSS, attachCustomCSSChange } from "./CustomStyle.js";
 import getStylesString from "./getStylesString.js";
 
+const effectiveStyleMap = new Map();
+
+attachCustomCSSChange(tag => {
+	effectiveStyleMap.delete(tag);
+});
+
 const getEffectiveStyle = ElementClass => {
 	const tag = ElementClass.getMetadata().getTag();
-	const customStyle = getCustomCSS(tag) || "";
 
-	const builtInStyles = getStylesString(ElementClass.styles);
-	return `${builtInStyles} ${customStyle}`;
+	if (!effectiveStyleMap.has(tag)) {
+		const customStyle = getCustomCSS(tag) || "";
+		const builtInStyles = getStylesString(ElementClass.styles);
+		const effectiveStyle = `${builtInStyles} ${customStyle}`;
+		effectiveStyleMap.set(tag, effectiveStyle);
+	}
+
+	return effectiveStyleMap.get(tag);
 };
 
 export default getEffectiveStyle;
diff --git a/packages/main/bundle.es5.js b/packages/main/bundle.es5.js
index 21cf02da3990..2d783f0a8303 100644
--- a/packages/main/bundle.es5.js
+++ b/packages/main/bundle.es5.js
@@ -12,6 +12,8 @@ import { getFirstDayOfWeek } from "@ui5/webcomponents-base/dist/config/FormatSet
 import { getRegisteredNames as getIconNames } from  "@ui5/webcomponents-base/dist/SVGIconRegistry.js";
 import applyDirection from "@ui5/webcomponents-base/dist/locale/applyDirection.js";
 import ResizeHandler from "@ui5/webcomponents-base/dist/delegate/ResizeHandler.js";
+import { addCustomCSS } from "@ui5/webcomponents-base/dist/Theming.js";
+
 const configuration = {
 	getAnimationMode,
 	setAnimationMode,
@@ -25,7 +27,7 @@ const configuration = {
 };
 export {
 	configuration,
-	getIconNames,
 	applyDirection,
 	ResizeHandler,
+	addCustomCSS,
 };
diff --git a/packages/main/bundle.esm.js b/packages/main/bundle.esm.js
index 22382ba85607..3d7789c2f187 100644
--- a/packages/main/bundle.esm.js
+++ b/packages/main/bundle.esm.js
@@ -97,6 +97,7 @@ import { getFirstDayOfWeek } from "@ui5/webcomponents-base/dist/config/FormatSet
 import { getRegisteredNames as getIconNames } from  "@ui5/webcomponents-base/dist/SVGIconRegistry.js";
 import applyDirection from "@ui5/webcomponents-base/dist/locale/applyDirection.js";
 import ResizeHandler from "@ui5/webcomponents-base/dist/delegate/ResizeHandler.js";
+import { addCustomCSS } from "@ui5/webcomponents-base/dist/Theming";
 window["sap-ui-webcomponents-bundle"] = {
 	configuration : {
 		getAnimationMode,
@@ -109,8 +110,8 @@ window["sap-ui-webcomponents-bundle"] = {
 		getRTL,
 		getFirstDayOfWeek,
 	},
-	getIconNames,
 	getLocaleData,
 	applyDirection,
 	ResizeHandler,
+	addCustomCSS,
 };
diff --git a/packages/main/test/pages/CustomCSS.html b/packages/main/test/pages/CustomCSS.html
new file mode 100644
index 000000000000..da5010dda427
--- /dev/null
+++ b/packages/main/test/pages/CustomCSS.html
@@ -0,0 +1,53 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta http-equiv="X-UA-Compatible" content="IE=edge">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
+    <meta charset="utf-8">
+
+    <title>Button</title>
+
+    <script data-ui5-config type="application/json">
+        {
+            "language": "EN",
+            "noConflict": {
+                "events": ["click"]
+            },
+            "calendarType": "Islamic"
+        }
+    </script>
+
+	<script src="../../webcomponentsjs/webcomponents-loader.js"></script>
+	<script src="../../resources/bundle.esm.js" type="module"></script>
+    <script nomodule src="../../resources/bundle.es5.js"></script>
+
+</head>
+
+<body style="background-color: var(--sapBackgroundColor);">
+
+	<ui5-select id="select">
+		<ui5-option>1</ui5-option>
+		<ui5-option>2</ui5-option>
+	</ui5-select>
+
+	<br />
+	<br />
+
+	<ui5-button id="btn">Apply custom css and rerender</ui5-button>
+
+	<br />
+	<br />
+
+	<script>
+		const applyCustomCSSAndRerender = function() {
+			window["sap-ui-webcomponents-bundle"].addCustomCSS("ui5-select", ".ui5-select-root { background-color: red; } ");
+		};
+
+		document
+			.getElementById("btn")
+			.addEventListener("click", applyCustomCSSAndRerender);
+
+	</script>
+
+</body>
+</html>