delete card

src/client/styles/scss/theme/island.scss

@@ -88,12 +88,6 @@ html[dark] {
     }
   }
 
-  .card,
-  .card-header {
-    background: none;
-    border: none;
-  }
-
   .rbt-menu {
     background: lighten($color-themelight, 5%);
   }