前言
- pc端的布局大致是靠浮动，和定位来实现的，在这里我总结了一点点方法。
两列布局
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>两列布局</title>
<style>
.one{
width: 200px;
height: 200px;
border: 1px solid red;
float: left;
}
.tow{
width: 200px;
height: 300px;
border: 1px solid green;
float: right;
}
</style>
</head>
<body>
<div class="one"></div>
<div class="tow"></div>
</body>
</html>
三列布局
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge" />
<title>三列布局</title>
<style>
.box1 {
width: 200px;
height: 200px;
border: 1px solid;
float: left;
}
.box2 {
height: 200px;
width: 200px;
border: 1px solid;
float: right;
}
.box3 {
height: 200px;
overflow: hidden;
border: 1px solid;
}
/* 如果按照左中右的顺序来的话这个三列布局是实现不了的，中间的会被两端的把位置都占了
所以可以把中间的换到最后去，设置fbc，然后就能实现了*/
</style>
</head>
<body>
<div class="box1"></div>
<div class="box2"></div>
<div class="box3"></div>
</body>
</html>
相对定位和绝对定位
1.元素p任意放置位置
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
* {
margin: 0;
}
div {
/*设置参照物,相对定位*/
position: relative;
height: 400px;
width: 800px;
background: gray;
}
p {
/*设置为绝对定位,可以通过left,right,top,bottom*/
position: absolute;
height: 100px;
width: 100px;
background: green;
left: 20px;
right: 20px;
/*top: 20px;*/
bottom: 20px;
}
</style>
</head>
<body>
<div class="box">
<p>
</p>
</div>
</body>
</html>
2.子元素在父元素内居中
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
div {
width: 400px;
height: 400px;
border: 1px solid;
position: relative;
}
p {
position: absolute;
top: 50%;
left: 50%;
margin-top: -50px;
margin-left: -50px;
width: 100px;
height: 100px;
background: green;
}
</style>
</head>
<body>
<div>
<p>
</p>
</div>
</body>
</html>
固定定位
1.返回顶部按钮
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
a {
position: fixed;
bottom: 15px;
right: 15px;
}
</style>
</head>
<body>
<a href="#">返回顶部</a>
</body>
</html>
2.蒙层制作(固定定位)
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
div {
position: fixed;
left: 0;
right: 0;
top: 0;
bottom: 0;
background: #000;
opacity: 0.7;
}
</style>
</head>
<body>
<div>
</div>
<ul>
<li>xxxxxxxxxxxxxxxxxxx</li>
<li>xxxxxxxxxxxxxxxxxxx</li>
<li>xxxxxxxxxxxxxxxxxxx</li>
<li>xxxxxxxxxxxxxxxxxxx</li>
<li>xxxxxxxxxxxxxxxxxxx</li>
<li>xxxxxxxxxxxxxxxxxxx</li>
<li>xxxxxxxxxxxxxxxxxxx</li>
<li>xxxxxxxxxxxxxxxxxxx</li>
<li>xxxxxxxxxxxxxxxxxxx</li>
<li>xxxxxxxxxxxxxxxxxxx</li>
</ul>
</body>
</html>
z-index
- 通过z-index调整定位元素的优先级别
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
div {
position: fixed;
}
.box1 {
background: gray;
height: 100px;
width: 100px;
z-index: 3;
}
.box2 {
background: green;
height: 200px;
width: 200px;
z-index: 2;
}
.box3 {
background: yellow;
height: 300px;
width: 300px;
}
</style>
</head>
<body>
<div class="box1">
box1
</div>
<div class="box2">
box2
</div>
<div class="box3">
box3
</div>
</body>
</html>
浮动和清除浮动
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
/*让.left在左边,让.right在右边*/
div {
width: 200px;
height: 200px;
background: green;
border: 1px solid;
}
.left {
/*左浮动*/
float: left;
}
.right {
/*右浮动*/
float: right;
background: gray;
width: 300px;
height: 300px;
}
.main {
/*清除浮动*/
clear: both;
height: 400px;
width: 100%;
background: orange;
}
</style>
</head>
<body>
<div class="left">
左边
</div>
<div class="right">
右边
</div>
<div class="main">
</div>
</body>
</html>
项目中常用清除浮动的技巧
定义一个清除浮动的class
.clear:after {
display: block;
content: '';
clear: both;
visibility: hidden;
}
- 若某个元素使用了浮动，就给它的父元素添加这个class代码如下
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
.left {
float: left;
height: 100px;
width: 100px;
background: #008000;
}
.clear:after {
display: block;
content: '';
clear: both;
visibility: hidden;
}
.main {
height: 150px;
background: gray;
}
</style>
</head>
<body>
<div class="box clear">
<div class="left">
左边
</div>
</div>
<div class="main">
</div>
</body>
</html>
