<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>标题</title>
<style type="text/css">
#fontpage {
width: 0;
height: 0;
border-left: 50px solid transparent;
border-right: 50px solid transparent;
border-bottom: 100px solid #23a9f2;
}
</style>
</head>
<body>
<!-- div 标签用来标记区域 -->
<div id="fontpage">
</div>
</body>
</html>
effect:
