Fix sorting behavior on enumeration page

Sorting a list item on administration/enumerations page causes for the
tables at second and third position on the page an unexpected behavior
when trying to sort an element by drag & drop.

That is, the distance between the dragged element and its placeholder
increases that much that it was difficult to position the list item as
wished.

src/sass/components/_content.scss

@@ -35,6 +35,7 @@
     $side-space: $sidebar-width + $padding-side * 2;
     flex: 1 1 auto;
     width: calc(100% - #{$side-space});
+    overflow-x: auto; // needed for drag & drop of enumerations
   } @else {
     overflow: hidden;
   }