fix spinner

Author: kaeizen

src/components/design-library-list/editor.scss

@@ -246,8 +246,11 @@
   		will-change: opacity;
 		opacity: 1;
 		display: flex;
+		background-color: #fff;
+		z-index: 1;
 		&.stk-hide-spinner {
 			opacity: 0;
+			z-index: -1;
 		}
 		.components-spinner {
 			margin: auto;