fix ref url

src/css/theme-default.css

@@ -1,4 +1,4 @@
-/*UI设计参考：http://www.materialup.com/posts/a-or-b-bottom-music-player-dashboard*/
+/*UI设计参考：https://dribbble.com/shots/2365362-A-or-B-Bottom-music-player-dashboard*/
 
 .meplayer-container {
     font-family: Helvetica, Tahoma, Arial, STXihei, '华文细黑', 'Microsoft YaHei', '微软雅黑', SimSun, '宋体', Heiti, '黑体', sans-serif;