.circle{
width: 100px;
height: 50px;
border:1px solid black;
border-radius: 100px;
position:relative;
border-bottom:50px solid black;
}
.circle::before{
float:left;
content: ‘‘;
width: 10px;
height: 10px;
border: 20px solid black;
border-radius: 50px;
position: relative;
top:50%;
left:0;
background-color:#fff;
}
.circle::after{
float:right;
content: ‘‘;
width: 10px;
height: 10px;
border: 20px solid #fff;
border-radius:50px;
position: relative;
top:50%;
left:0;
background-color:#000;
}
原文：http://www.cnblogs.com/tl2f/p/4681812.html