[FIX] website snippet: drop zone for column with firefox

bzr revid: chm@openerp.com-20130920100821-qyy7n8j8612pzg3k

addons/website/static/src/css/editor.css

@@ -231,6 +231,10 @@ table.editorbar-panel td.selected {
 }
 
 /* ---- SNIPPETS DROP ZONES ---- */
+.col-md-12[data-snippet-id="colmd"] {
+  float: left;
+}
+
 .oe_drop_zone.oe_insert {
   display: block;
   height: 48px;
@@ -241,7 +245,7 @@ table.editorbar-panel td.selected {
   position: absolute;
   z-index: 1000;
 }
-.oe_drop_zone.oe_insert:before {
+.oe_drop_zone.oe_insert:not(.oe_vertical):before {
   content: "";
   display: block;
   border-top: dashed 2px rgba(209, 178, 255, 0.72);
@@ -252,10 +256,10 @@ table.editorbar-panel td.selected {
   border-top: dashed 2px rgba(116, 255, 161, 0.72);
 }
 .oe_drop_zone.oe_insert.oe_vertical {
-  width: 16px;
-  display: inline-block;
-  position: absolute;
-  margin: 0px !important;
+  width: 24px;
+  float: left;
+  position: relative;
+  margin: 0px -12px !important;
 }
 .oe_drop_zone.oe_insert.oe_overlay {
   background: rgba(153, 0, 255, 0.17);