css改变下拉框的下拉小三角样式

select{
width: 90%;
padding: 8px 0;
font-size: 14px;
border: none;
outline: none;
appearance: none;
-webkit-appearance: none;
-moz-appearance: none;
}
div:after{
content: "";
width: 13px;
height: 7px;
background: url(../../../images/about/sanjiaoxing2.png) no-repeat center;
-webkit-background-size: 100% 100%;
background-size: 100% 100%;
position: absolute;
right: 20px;
top: 45%;
//给自定义的图标实现点击下来功能
pointer-events: none;
}