chore: make color box size bigger

Author: abose

src/styles/Extn-CSSColorPreview.less

@@ -15,8 +15,8 @@
     }
     display: inline-block;
     top: .1em;
-    height:.7em;
-    width: .7em;
+    height:.8em;
+    width: .8em;
     position: relative;
     pointer-events: auto;
 }