Change list item (collapsed, expanded) image to background-image for better browser compatibility

Changed from

.region-sidebar-first ul.menu, .region-sidebar-second ul.menu {  margin:0; padding:0; }

.region-sidebar-first ul.menu li, .region-sidebar-second ul.menu li { list-style:none; margin:0; padding:5px; border-bottom:1px solid #e7e7e7; display:block; }

.region-sidebar-first ul.menu ul.menu, .region-sidebar-second ul.menu ul.menu { padding:0 0 0 15px; }

.region-sidebar-first ul.menu li.collapsed a, .region-sidebar-second ul.menu li.collapsed a, #footer .block ul.menu li.collapsed a { background: url(images/menu-collapsed.png) no-repeat; }

.region-sidebar-first ul.menu li.expanded a, .region-sidebar-second ul.menu li.expanded a, #footer .block ul.menu li.expanded a { background: url(images/menu-collapsed.png) no-repeat; }

To

.region-sidebar-first ul.menu, .region-sidebar-second ul.menu {  margin:0; padding:0; }

.region-sidebar-first ul.menu li, .region-sidebar-second ul.menu li { list-style:none; margin:0; padding:5px; border-bottom:1px solid #e7e7e7; display:block; }

.region-sidebar-first ul.menu ul.menu, .region-sidebar-second ul.menu ul.menu { padding:0 0 0 15px; }

.region-sidebar-first ul.menu li.collapsed, .region-sidebar-second ul.menu li.collapsed, #footer .block ul.menu li.collapsed { background:url("images/menu-collapsed.png") no-repeat scroll left 10px transparent; }

.region-sidebar-first ul.menu li.expanded, .region-sidebar-second ul.menu li.expanded, #footer .block ul.menu li.expanded { background:url("images/menu-expanded.png") no-repeat scroll left 10px transparent; }

.region-sidebar-first ul.menu li.collapsed > a, .region-sidebar-second ul.menu li.collapsed > a, #footer .block ul.menu li.collapsed > a { padding-left:15px; }

.region-sidebar-first ul.menu li.expanded > a, .region-sidebar-second ul.menu li.expanded > a, #footer .block ul.menu li.expanded > a { padding-left:15px; }

Just committed http://drupalcode.org/project/corporateclean.git/commit/8b220ce