replace background and not just color

Author: haroun

modules/@apostrophecms/ui/ui/apos/scss/global/_device_preview.scss

@@ -1,5 +1,5 @@
 body[data-device-preview-mode] {
-  background-color: var(--a-base-10);
+  background: var(--a-base-10);
 
   [data-apos-refreshable] {
     container-type: size;