使用css样式线性渐变方法画出div的对角线

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟教程(runoob.com)</title>
<style>
#grad1 {
height: 100px;
width: 100px;
border: #333 1px solid;
background-image: linear-gradient(45deg,transparent 50%, #333 50%, #333 50.1%, transparent 50%);
}
</style>
</head>

<body>
<h3>线性渐变</h3>
<p>画出div的对角线</p>

<p><strong>注意：</strong> Internet Explorer 9 及更早版本 IE 浏览器不支持渐变。</p>
</body>
</html>