Issue 2408 - Improved accessibility of checkboxes in options page

skin/options.css

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2015 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 74 matching lines @@
   display: none;
 }
 
 input[type="text"], input[type="search"]
 {
   -webkit-box-sizing: border-box;
   -moz-box-sizing: border-box;
   box-sizing: border-box;
 }
 
+button[role="checkbox"]
+{
+  vertical-align: top;
+  width: 18px;
+  height: 18px;
+  margin-top: 0px;
+  -moz-margin-end: 20px;
+  -webkit-margin-end: 20px;
+  padding: 0px;
+  border: none;
+  background-color: transparent;
+  background-position: -51px 0px;
+}
+
+button[role="checkbox"][aria-checked="true"]
+{
+  background-position: -68px 0px;
+}
+
 .option-name
 {
   display: flex;
   margin-bottom: 16px;
   margin-top: 24px;
 }
 
 .option-name > :first-child
 {
   flex: 1;
@@ skipping 157 matching lines @@
 {
   display: none;
 }
 
 #tab-share:lang(zh) + li,
 #tab-share[hidden] + li
 {
   border-top: none;
 }
 
-#tab-content
+#content
 {
   background-color: #FFFFFF;
   border: 1px solid #CDCDCD;
   border-radius: 8px;
   box-sizing: border-box;
   min-width: 960px;
   padding: 0px 60px 40px 60px;
 }
 
-#tab-content h1
+#content h1
 {
   border-bottom: 1px solid #CDCDCD;
   margin: 0px;
   padding: 40px 0px 16px 0px;
 }
 
 #link-version
 {
   display: flex;
   margin: 12px 20px;
@@ skipping 174 matching lines @@
 }
 
 .tabs.horizontal li.active
 {
   border-bottom: 2px solid #1E8728;
   color: black;
   font-weight: 600;
   padding-bottom: 10px;
 }
 
-.icon, .table input[type="checkbox"]::before, .table button.delete,
+.icon, .table button[role="checkbox"], .table button.delete,
 #content-help a::before, #dialog-close::before,
 #custom-filters-add button::after,
 #dialog-body button::before
 {
   background-image: url(options-sprite.png);
   display: inline-block;
 }
 
 .icon-add
 {
@@ skipping 614 matching lines @@
 #other-language .button-add::before
 {
   display: none;
 }
 
 #other-language .display
 {
   -webkit-margin-start: 10px;
   -moz-margin-start: 10px;
 }