diff --git a/packages/customize-widgets/src/components/sidebar-block-editor/style.scss b/packages/customize-widgets/src/components/sidebar-block-editor/style.scss
index 8e6f1905e2799a..6f200ba31144a6 100644
--- a/packages/customize-widgets/src/components/sidebar-block-editor/style.scss
+++ b/packages/customize-widgets/src/components/sidebar-block-editor/style.scss
@@ -3,11 +3,3 @@
 	// Appear over block placeholders, but under widgets page headings.
 	z-index: 8;
 }
-
-.customize-control-sidebar_block_editor {
-	margin: 0 ( -$grid-unit-15 ) ( -$grid-unit-15 ) ( -$grid-unit-15 );
-	padding: $grid-unit-15;
-	background: $white;
-	border-top: 1px solid #dcdcde;
-	border-bottom: 1px solid #dcdcde;
-}
diff --git a/packages/customize-widgets/src/controls/sidebar-section.js b/packages/customize-widgets/src/controls/sidebar-section.js
index 0e97130e0d114f..4d1b00ed716ed4 100644
--- a/packages/customize-widgets/src/controls/sidebar-section.js
+++ b/packages/customize-widgets/src/controls/sidebar-section.js
@@ -32,6 +32,9 @@ export default function getSidebarSection() {
 				}
 			);
 			customize.section.add( this.inspector );
+			this.contentContainer[ 0 ].classList.add(
+				'customize-widgets__sidebar-section'
+			);
 		}
 		hasSubSectionOpened() {
 			return this.inspector.expanded();
diff --git a/packages/customize-widgets/src/controls/style.scss b/packages/customize-widgets/src/controls/style.scss
new file mode 100644
index 00000000000000..d30592205a6c17
--- /dev/null
+++ b/packages/customize-widgets/src/controls/style.scss
@@ -0,0 +1,6 @@
+// Adds a white background to the block based widget section.
+// #customize-theme-controls id is required to add specificity.
+#customize-theme-controls .customize-widgets__sidebar-section {
+	min-height: 100%;
+	background-color: $white;
+}
diff --git a/packages/customize-widgets/src/style.scss b/packages/customize-widgets/src/style.scss
index be1dad99a50136..c75380757e8c10 100644
--- a/packages/customize-widgets/src/style.scss
+++ b/packages/customize-widgets/src/style.scss
@@ -2,3 +2,4 @@
 @import "./components/block-inspector-button/style.scss";
 @import "./components/header/style.scss";
 @import "./components/inserter/style.scss";
+@import "./controls/style.scss";