<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>五角星</title>
<style>
#star-five {
margin: 50px;
position: relative;
display: block;
color: red;
width: 0;
height: 0;
border-right: 100px solid transparent;
border-bottom: 70px solid red;
border-left: 100px solid transparent;
/*-moz-transform: rotate(35deg);*/
/*-webkit-transform: rotate(35deg);*/
/*-ms-transform: rotate(35deg);*/
/*-o-transform: rotate(35deg);*/
transform: rotate(35deg);
}
#star-five:before {
border-bottom: 80px solid red;
border-left: 30px solid transparent;
border-right: 30px solid transparent;
position: absolute;
height: 0;
width: 0;
top: -45px;
left: -65px;
display: block;
/*下面这条代码是必须的，表示在#star-five盒子之前插入一个非空的盒子*/
content: ‘‘;
-webkit-transform: rotate(-35deg);
-moz-transform: rotate(-35deg);
-ms-transform: rotate(-35deg);
-o-transform: rotate(-35deg);
}
#star-five:after {
position: absolute;
display: block;
color: red;
top: 3px;
left: -105px;
width: 0;
height: 0;
border-right: 100px solid transparent;
border-bottom: 70px solid red;
border-left: 100px solid transparent;
-webkit-transform: rotate(-70deg);
-moz-transform: rotate(-70deg);
-ms-transform: rotate(-70deg);
-o-transform: rotate(-70deg);
content: ‘‘;
}
</style>
</head>
<body>
<div id="star-five"></div>
</body>
</html>原文：http://www.cnblogs.com/webbest/p/5638777.html