better sizing for palette options

www/canvas/index.html

@@ -41,8 +41,8 @@
             padding-left: 75px;
         }
         span.palette {
-            height: 50px;
-            width: 50px;
+            height: 4vw;
+            width: 4vw;
             display: inline-block;
             margin: 5px;
             border: 2px solid black;