Cached CSS is no longer a problem

The !important is retained for cached HTML and will be retained
for another release cycle

Cached HTML will continue to be a problem until next deploy. The CSS
cleanup will thus be fixed in a follow up
(I47b7a0bc9c5dad5451f1dbb5e32e513643a1534b)

Bug: T307900
Change-Id: I47b7a0bc9c5dad5451f1dbb5e32e513643a1534b

includes/templates/ContentHeader.mustache

@@ -22,8 +22,7 @@
 		aria-controls="toc-toggle-list"
 		data-event-name="vector.toc-toggle-list"
 		tabindex="0"
-		title="{{msg-vector-toc-menu-tooltip}}"
-		style="display: none">
+		title="{{msg-vector-toc-menu-tooltip}}">
 	</label>
 	{{/data-toc}}
     {{{html-title-heading}}}