<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>用边框绘制的三角形</title>
<style type="text/css">
div.arrow{width:0; border-bottom:20px solid #000; border-left:20px solid #fff; border-right:20px solid #fff;}
div.square{width:40px; height:20px; background:#000;}
</style>
</head>
<body>
<div class="arrow" title="用边框绘制的三角形"></div>
<div class="square"></div>
</body>
</html>
备注：代表三角形的那个DIV width属性要为0；border-bottom的颜色为三角形的颜色，border-left和border-right的颜色为背景色。
