Fixed Color Picker issue (#82)

* Fixed Color Picker issue

* Fix lint check

Author: Yahiewi

style/base.css

@@ -128,3 +128,9 @@
   max-height: 50vh;
   overflow: scroll;
 }
+
+/* Expand hover area to reach color pickers */
+.urdf-gui .cr.color .c:hover {
+  padding: 15px 0;
+  margin: -15px 0;
+}