border-box
感受一下下面的代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
.div{
height: 200px;
width: 200px;
background: red;
margin: 10px;
border: 1px solid #000;
padding: 20px;
}
#div1 {
box-sizing: border-box;
height: 200px;
width: 200px;
background: red;
margin: 10px;
border: 1px solid #000;
padding: 20px;
}
#div2 {
box-sizing: content-box;
height: 200px;
width: 200px;
background: red;
margin: 10px;
border: 1px solid #000;
padding: 20px;
}
</style>
<body>
<div class="div"></div>
<div id="div1">border-box</div>
<div id="div2">content-box</div>
</body>
</html>
inline 元素 padding
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
*{
padding:0;
}
span{
padding-top:20px;
padding-right: 20px;
padding-bottom: 20px;
padding-left: 20px;
}
</style>
</head>
<body>
<span>哈哈哈哈</span>
<div>123</div>
</body>
</html>
<!--
对于inline 元素 垂直padding 不影响尺寸，失效的
但是 垂直方向影响了背景色区域
-->
padding 不支持 负值
--------------------------------------------------------------------------------------------------------------------------
div{
padding:50%;
background:red;
}
//永远是正方形
inline元素的文字断行
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>JS Bin</title>
<style>
span{
padding:50%;
background:red;
}
</style>
</head>
<body>
<span>
文字若干
</span>
</body>
</html>
inline元素设置padding:50%(元素内无文字)，不像div一样是正方形。解决办法是font-size:0（给父级）;
不使用伪元素 实现三线
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>JS Bin</title>
<style>
div{
width:150px;
height:30px;
padding:15px 0;
border-top: 30px solid;
border-bottom: 30px solid;
background-clip: content-box;
background-color: black;
}
</style>
</head>
<body>
<div></div>
</body>
</html>
同样，不用为元素实现眼睛
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>JS Bin</title>
<style>
div{
width:150px;
height:150px;
padding:10px;
border:10px solid;
border-radius: 50%;
background-clip: content-box;
background-color: black;
}
</style>
</head>
<body>
<div></div>
</body>
</html>
