Small CSS optimizations

- Remove unneeded "background-position: 0 0" declarations
- Shorter image replacement text-indent with ems
- Fix nav overqualified elements (4 CSSlint warnings less)

flexslider.css

@@ -47,15 +47,15 @@ filter:progid:DXImageTransform.Microsoft.gradient(startColorstr=#4C000000,endCol
 .flex-caption {width: 96%; padding: 2%; position: absolute; left: 0; bottom: 0; background: rgba(0,0,0,.3); color: #fff; text-shadow: 0 -1px 0 rgba(0,0,0,.3); font-size: 14px; line-height: 18px;}
 
 /* Direction Nav */
-.flex-direction-nav li a {width: 52px; height: 52px; margin: -13px 0 0; display: block; background: url(theme/bg_direction_nav.png) no-repeat 0 0; position: absolute; top: 50%; cursor: pointer; text-indent: -9999px;}
-.flex-direction-nav li a.next {background-position: -52px 0; right: -21px;}
-.flex-direction-nav li a.prev {background-position: 0 0; left: -20px;}
-.flex-direction-nav li a.disabled {opacity: .3; filter:alpha(opacity=30); cursor: default;}
+.flex-direction-nav li a {width: 52px; height: 52px; margin: -13px 0 0; display: block; background: url(theme/bg_direction_nav.png) no-repeat; position: absolute; top: 50%; cursor: pointer; text-indent: -999em;}
+.flex-direction-nav li .next {background-position: -52px 0; right: -21px;}
+.flex-direction-nav li .prev {left: -20px;}
+.flex-direction-nav li .disabled {opacity: .3; filter:alpha(opacity=30); cursor: default;}
 
 /* Control Nav */
 .flex-control-nav {width: 100%; position: absolute; bottom: -30px; text-align: center;}
 .flex-control-nav li {margin: 0 0 0 5px; display: inline-block; zoom: 1; *display: inline;}
 .flex-control-nav li:first-child {margin: 0;}
-.flex-control-nav li a {width: 13px; height: 13px; display: block; background: url(theme/bg_control_nav.png) no-repeat 0 0; cursor: pointer; text-indent: -9999px;}
+.flex-control-nav li a {width: 13px; height: 13px; display: block; background: url(theme/bg_control_nav.png) no-repeat; cursor: pointer; text-indent: -999em;}
 .flex-control-nav li a:hover {background-position: 0 -13px;}
-.flex-control-nav li a.active {background-position: 0 -26px; cursor: default;}
+.flex-control-nav li .active {background-position: 0 -26px; cursor: default;}