<html lang="en">
<head>
<meta charset="UTF-8">
<title>test</title>
<style>
div {
text-align: center
margin-bottom: 20px
width: 100px
height: 100px
line-height: 100px
}
.a {
/*圆点*/
border: 10px dotted red
}
.b {
/*实线*/
border: 10px solid red
}
.c {
/*双实线*/
border: 10px double red
}
.d {
/*虚线*/
border: 10px dashed red
}
</style>
</head>
<body>
<div class="a">
圆点
</div>
<div class="b">
实线
</div>
<div class="c">
双实线
</div>
<div class="d">
虚线
</div>
</body>
</html>
