结论
width的%：定义基于包含块（父元素）宽度的百分比宽度，会突破父级的限制 width的auto：尽量被父级包裹 height的%：基于包含它的块级对象的百分比高度，会突破父级的限制 height的auto：尽量被父级包裹案例
一定复制代码跑一遍，花几分钟体会一下尽量被父级包裹与突破父级的限制
width案例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
* {
margin: 0;padding: 0;
}
body {
background: #dcdcdc;
}
.box {
width: 400px;
border: 3px solid red;
padding: 0 50px;
}
.box1 {
width: auto;
height: 100px;
background: pink;
padding: 0 50px;
margin: 0 50px;
border-width: 0 50px;
border-style: solid;
border-color: green;
}
.box2 {
width: 100%;
height: 100px;
background: gold;
padding: 0 50px;
margin: 0 50px;
border-width: 0 50px;
border-style: solid;
border-color: green;
}
</style>
</head>
<body>
<div class="box">
<div class="box1"></div>
<div class="box2"></div>
</div>
</body>
</html>
height案例
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
* {
margin: 0;padding: 0;
}
body {
background: #dcdcdc;
}
.box {
width: 400px;
border: 3px solid red;
padding: 50 0px;
height: 400px;
}
.box1 {
width: 200px;
height:auto;
background: pink;
padding: 50px 0px;
margin: 50px 0px;
border-width: 50px 0px;
border-style: solid;
border-color: green;
}
.box2 {
width: 200px;
height:100%;
background: gold;
padding: 50px 0px;
margin: 50px 0px;
border-width: 50px 0px;
border-style: solid;
border-color: green;
}
</style>
</head>
<body>
<div class="box">
<div class="box1"></div>
<div class="box2"></div>
</div>
</body>
</html>
