Wrap playground links in buttons.

Author: gkellogg

index.html

@@ -184,14 +184,12 @@
   a.playground {
     border-bottom: none;
     text-decoration: none;
-    background: url("json-ld-data-16.png");
-    width: 16px;
-    height: 16px;
-    display: inline-block;
+    font-size: 13px;
   }
   a[href].playground {
     border-bottom: none;
     text-decoration: none;
+    color: #666;
   }
 </style>
 </head>