图标旋转

.nav_bar .rotate-triangle {position:absolute;width:13px; height:8px; top:30px; right:8px; background: url(../images/ico_triangle.png) no-repeat;-moz-transition:all 0.4s ease 0s; -webkit-transition:all 0.4s ease 0s; transition:all 0.4s ease 0s;}

.nav_bar .nav-items .over .rotate-triangle { -moz-transform: rotate(180deg); -webkit-transform: rotate(180deg); transform: rotate(180deg); }

<span class="rotate-triangle"></span>

通过脚本加个over类