盒子模型
1. 什么是盒子模型
margin:外边距
padding:内边距
border:边框
2. 边框
- 边框的样式
- 边框的粗细
- 边框的颜色
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
/*常见操作,初始化0*/
h1, ul, li, a, body{
/*body总有一个默认的外边距,这里使之为0*/
margin: 0;
padding: 0;
text-decoration: none;
}
/*border: 粗细 样式 颜色*/
#box{
300px;
border: 1px solid red;
}
h2{
font-size: 16px;
background-color: rosybrown;
line-height: 30px;
margin: 0;
}
form{
background: greenyellow;
}
/*solid实线*/
div:nth-of-type(1) input{
border: 3px solid black;
}
/*dashed虚线*/
div:nth-of-type(2) input{
border: 3px dashed yellow;
}
div:nth-of-type(3) input{
border: 2px dashed violet;
}
</style>
</head>
<body>
<div id="box">
<h2>会员登录</h2>
<form action="#">
<div>
<span>用户名:</span>
<input type="text">
</div>
<div>
<span>密码:</span>
<input type="password">
</div>
<div>
<span>邮箱:</span>
<input type="text">
</div>
</form>
</div>
</body>
</html>
3. 内外边距
外边距的妙用:居中元素
margin: 0 auto;
利用margin居中的要求
- 块元素(div)
- 块元素有固定的宽度
- 写在style的div中
margin顺时针旋转
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<!--
外边距的妙用:居中元素
margin: 0 auto;
margin顺时针旋转
-->
<style>
#box{
300px;
border: 1px solid red;
margin: 0 auto;
}
h2{
font-size: 16px;
background-color: rosybrown;
line-height: 30px;
margin: 0;
}
form{
background: greenyellow;
}
input{
border: 1px solid black;
}
</style>
</head>
<body>
<div id="box">
<h2>会员登录</h2>
<form action="#">
<div>
<span>用户名:</span>
<input type="text">
</div>
<div>
<span>密码:</span>
<input type="password">
</div>
<div>
<span>邮箱:</span>
<input type="text">
</div>
</form>
</div>
</body>
</html>
盒子的计算方式:当前元素到底多大?
margin+border+padding+内容宽度
4. 圆角边框
4个角
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
div{
100px;
height: 50px;
border: 10px solid red;
border-radius: 50px 50px 0px 0px;
margin: 0 auto;
}
/*图片削圆角*/
img{
border-radius: 200px;
}
</style>
</head>
<body>
<div></div>
<img src="images/book_cover.jpg" alt="">
</body>
</html>
5. 盒子阴影
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
div{
500px;
height: 1000px;
margin: 0 auto;
}
img{
100px;
height: 100px;
border: 10px solid red;
border-radius: 200px;
box-shadow: 10px 10px 100px yellow;
}
</style>
</head>
<body>
<div>
<img src="images/book_cover.jpg" alt="">
</div>
</body>
</html>