Restore a rule for the title block.

This fixes an issue with TwentyNineteen.

packages/edit-post/src/components/visual-editor/style.scss

@@ -54,6 +54,18 @@
 	}
 }
 
+
+// The base width of the title should match that of blocks even if it isn't a block.
+// @todo: This duplicates CSS from line 49 in block-list/style.scss, and should be
+// removed when the Title field becomes an actual block.
+.editor-post-title {
+	// Beyond the mobile breakpoint, compensate for side UI.
+	@include break-small() {
+		padding-left: $block-padding + $block-side-ui-width + $block-padding + $border-width * 2;
+		padding-right: $block-padding + $block-side-ui-width + $block-padding + $border-width * 2;
+	}
+}
+
 .edit-post-visual-editor .editor-post-title__block {
 	// Center.
 	margin-left: auto;