diff --git a/packages/block-editor/src/components/inserter/preview-panel.js b/packages/block-editor/src/components/inserter/preview-panel.js
index 5780949ac891a..612b435d06dcc 100644
--- a/packages/block-editor/src/components/inserter/preview-panel.js
+++ b/packages/block-editor/src/components/inserter/preview-panel.js
@@ -49,9 +49,11 @@ function InserterPreviewPanel( { item } ) {
 							blocks={ blocks }
 							viewportWidth={ viewportWidth }
 							minHeight={ previewHeight }
-							additionalStyles={ [
-								{
-									css: `
+							additionalStyles={
+								//We want this CSS to be in sync with the one in BlockPreviewPanel.
+								[
+									{
+										css: `
 										body { 
 											padding: 24px;
 											min-height:${ Math.round( minHeight ) }px;
@@ -60,8 +62,9 @@ function InserterPreviewPanel( { item } ) {
 										}
 										.is-root-container { width: 100%; }
 									`,
-								},
-							] }
+									},
+								]
+							}
 						/>
 					</div>
 				) : (
diff --git a/packages/edit-site/src/components/global-styles/block-preview-panel.js b/packages/edit-site/src/components/global-styles/block-preview-panel.js
index 37691bfbfcbd7..82f429e0e2c04 100644
--- a/packages/edit-site/src/components/global-styles/block-preview-panel.js
+++ b/packages/edit-site/src/components/global-styles/block-preview-panel.js
@@ -50,9 +50,11 @@ const BlockPreviewPanel = ( { name, variation = '' } ) => {
 					blocks={ blocks }
 					viewportWidth={ viewportWidth }
 					minHeight={ previewHeight }
-					additionalStyles={ [
-						{
-							css: `
+					additionalStyles={
+						//We want this CSS to be in sync with the one in InserterPreviewPanel.
+						[
+							{
+								css: `
 								body{
 									padding: 24px;
 									min-height:100%;
@@ -61,8 +63,9 @@ const BlockPreviewPanel = ( { name, variation = '' } ) => {
 								}
 								.is-root-container { width: 100%; }
 							`,
-						},
-					] }
+							},
+						]
+					}
 				/>
 			</div>
 		</Spacer>