<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
div{
border: 1px solid red;
}
.div1{
width: 100px;
height:100px ;
/*margin是直接设置四周的外边距
margin: 50px;*/
}
.div2{
width: 200px;
height: 200px;
/*设置外边框 外边距会影响大小*/
padding: 50px;
/*设置盒子的属性，让width和height就是盒子最终的大小*/
box-sizing: border-box;
}
/* .是类选择器 */
.div3{
float: left;
}
.div4{
float: left;
}
.div5{
float: right;
}
</style>
</head>
<body>
<div class="div2">
<div class="div1">
</div>
</div>
<div class="div3">aaa</div>
<div class="div4">bbb</div>
<div class="div5">ccc</div>
</body>
</html>
