Fix style issue with drag&drop in the active folder

www/drive/file.css

@@ -131,7 +131,7 @@ span.fa-folder-open {
 #tree span.element {
   cursor: pointer;
 }
-#tree .active:not(.selected) {
+#tree .active:not(.selected):not(.droppable) {
   background-color: #c8c8c8;
 }
 #tree .category2 {

www/drive/file.less

@@ -167,7 +167,7 @@ span {
         cursor: pointer;
     }
     .active {
-        &:not(.selected) {
+        &:not(.selected):not(.droppable) {
             background-color: darken(@drive-hover, 15%);
         }
     }