eur-lex: don't hide the toc fully but shrink it to 0px vertically.

This makes it invisible too but doesn't make the toggle button be resized
since its container is still the same width.

eur-lex/eur-lex_toc.user.js

@@ -96,7 +96,7 @@ visibility_button.onclick = (function() {
   var visible = true;
   return function() {
     visible = ! visible;
-    toc_ltr.style = visible ? "" : "display: none;";
+    toc_ltr.style = visible ? "" : "height: 0px;";
   }
 })();