demo01.html:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>css课程</title>
<style type="text/css"></style>
<link rel="stylesheet" type="text/css" href="div1.css"/>
</head>
<body>
<div id="div1"align="center"style="text-align: center;">css样式表</div>
</body>
</html>
div1.css:
[style] {
200px;
height: 200px;
border: 1px;
border-style:dashed;
background-color: #FF0000;
border-radius: 3.125rem ;
/* 圆角 */
padding-bottom: initial;
/* 下边距 */
margin-bottom: 10px 20px 30px;
/* 上边距 */
float: right;
/* 浮动 */
}