Fix Group Pictures layout (theme-next#931)

Author: 1v9

source/css/_common/components/tags/group-pictures.styl

@@ -3,22 +3,18 @@
     box-sizing: border-box;
     padding: 0 3px;
     border: none;
+    margin: 0 auto;
   }
 }
 
-.post .group-picture-row {
+.post-body .group-picture-row {
   overflow: hidden;
-  margin-top: 6px;
-  &:first-child { margin-top: 0; }
+  margin-bottom: 6px;
 }
 
-.post .group-picture-column { float: left; }
-
-.page-post-detail .post-body .group-picture-column {
-  float: none;
-  margin-top: 10px;
-  width: auto !important;
-  img { margin: 0 auto; }
+.post-body .group-picture-column {
+  float: left;
+  margin-bottom: 10px;
 }
 
 .page-archive {