<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>边框和浮动</title>
<style>
.box{
width: 290px;
height: 290px;
border-right: 5px dashed blue;
border-top: 5px solid coral;
border-bottom: 5px dotted black;
border-left: 5px solid yellow;
float: left;
}
.a{
width: 300px;
height: 300px;
background-color: #23b2ff;
float: left;
}
.b{
width: 300px;
height: 300px;
background-color: #fff4b4;
float: left;
}
.c{
width: 300px;
height: 300px;
background-color: #36ff20;
clear: both;
}
</style>
</head>
<body>
<div class="box">
</div>
<div class="a">
</div>
<div class="b">
</div>
<div class="c">
</div>
</body>
</html>