Refactor platform visual styles by removing background and border for device animator

theme/assets/css/main.css

@@ -1986,6 +1986,8 @@ p:last-child { margin-bottom: 0; }
 
 /* ── 10b. Device Animator ───────────────────────────────────── */
 .platform-visual.has-anim {
+  background: none;
+  border: none;
   padding: 0;
   overflow: hidden;
   position: relative;