<!DOCTYPE html>
<html>
<head></head>
<style type="text/css">
#triangle{
width: 0px;
height: 0px;
border-bottom: 140px solid yellowgreen;
border-left: 70px solid transparent;
border-right: 70px solid transparent;
}
</style>
<body>
<div id="triangle"></div>
</body>
</html>
效果图
