css利用相对定位 overflow隐藏，制作向下箭头。同理可做上下左右方向箭头
/*html*/
<div class="site-nav-send">
送至：北京
<span><b>◇</b></span>
</div>
/*css*/
.site-nav-send{
width: 60px;
height: 30px;
padding: 0 25px 0 10px;
position: relative;
}
.site-nav-send span{
width: 13px;
height: 7px;
position: absolute;
overflow: hidden;
top:12px;
right: 6px;
font: 400 13px/15px "consolas";
}
.site-nav-send b{
width: 17px;
height: 15px;
position: absolute;
top:-7px;
}
