Update _res/_custom.css

_res/_custom.css

@@ -231,7 +231,8 @@ span.has-info+div {
         transition: transform 0.2s ease-in-out, width 0.3s ease-in-out, height 0.38s ease-in-out 0.1s;
         border-radius: 0.4rem;
         border: 4px solid var(--text-color-by-luminance);
-        background: transparent;
+        /*background: transparent;*/
+        background-position: center;
     }
 
     [data-aspect-ratio="16-9"] {
@@ -261,6 +262,7 @@ span.has-info+div {
     [data-aspect-ratio="1-1"] {
         width: 70px !important;
         height: 70px !important;
+        background-image: url("_res/assets/ratio_preview_bgs/70x70px_1zu1.png");
     }
 }