DevTools: render category filters in a way that they don't clash.

Source/devtools/front_end/sidebarPane.css

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2009 Anthony Ricaud <rik@webkit.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 91 matching lines @@
 
 .sidebar-pane-title::before {
     background-position: -4px -96px;
 }
 
 .sidebar-pane-title.expanded::before {
     background-position: -20px -96px;
 }
 
 .sidebar-pane-toolbar {
-    line-height: 18px;
     left: 0;
     right: 4px;
     top: 0;
-    height: 20px;
     position: absolute;
     pointer-events: none;
 }
 
 .sidebar-pane-toolbar > * {
     pointer-events: auto;
 }
 
 .sidebar-pane-toolbar > .pane-title-button,
 .sidebar-pane-toolbar > label {
@@ skipping 64 matching lines @@
     visibility: hidden;
 }
 
 .styles-section.matched-styles:not(.read-only):hover .sidebar-pane-button-new-rule {
     visibility: visible;
 }
 
 .sidebar-pane-button-new-rule:hover {
     background-position: -23px 0;
 }