add retina logo

css/common/common.less

@@ -49,10 +49,16 @@ body, html {
     top: 0;
 
     >.logo {
+        loat: left;
         width: 180px;
         height: 50px;
         background: url(./img/logo.png) no-repeat;
         float: left;
+        background-color: #fff;
+        background-position: center;
+        background-image: url(./img/logo@1x.png);
+        background-image: -webkit-image-set(url(./img/logo@1x.png) 1x, url(./img/logo@2x.png) 2x);
+        background-repeat: no-repeat;
     }
 
     >.action-groups {
@@ -148,7 +154,7 @@ body, html {
         background: rgba(112, 119, 128, 1);
         margin-top: -40px;
     }
-    
+
     .close-editor {
         position: absolute;
         right: 0;