console 命令行工具 X clear

console

<!DOCTYPE html>
<html>
<head>
    <title>css实现三角形</title>
</head>
<body>
<div></div>
</body>
</html>

/*记忆口诀：盒子宽高均为零，三面边框皆透明。 */
div{
    position: absolute;
    width: 0px;
    height: 0px;
    /* content: ""; */
    border-top: 100px solid transparent;
    border-right: 100px solid transparent;
    border-left: 100px solid transparent;
    border-bottom: 100px solid black;
}