<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
#triangle_up{
width:0;
border: 50px solid transparent;
border-bottom: 100px solid red;
}
</style>
</head>
<body>
<div id="triangle_up"></div>
</body>
</html>
在chrome浏览器下显示的结果.png
