您需要更加直接地使用CSS.另外，您还需要删除其中的默认图片

You need to be a little more direct with your CSS. Also you need to remove the default image that resides there

.ui-state-active, .ui-widget-content .ui-state-active, .ui-widget-header .ui-state-active {
      background-image: none;
      background-color:green;
    }

DEMO http://jsbin.com/iXur/25/edit