widgets: Remove box-shadow and use background-color to show focus.

The box-shadows cuts off on left and overlaps with button on right.
We instead change background-color in dark theme and border color in
white theme to show focus.

web/styles/widgets.css

@@ -112,9 +112,8 @@
         &:focus {
             border-color: hsl(206deg 80% 62% / 80%);
             outline: 0;
-            box-shadow:
-                inset 0 1px 1px hsl(0deg 0% 0% / 7.5%),
-                0 0 8px hsl(206deg 80% 62% / 60%);
+            box-shadow: none;
+            background-color: var(--color-background-widget-input);
         }
     }
 }