一、两栏布局的实现
两栏布局其实就是左侧定宽，右侧自适应的布局
1. float+margin
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> <style> .container { display: flex; height: 300px; } .left { width: 100px; background: red; } .right { flex: 1; background: green; } </style> </head> <body> <div class="container"> <div class="left"></div> <div class="right"></div> </div> </body> </html>
2. flaot+BFC
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> <style> .container { display: flex; height: 300px; } .left { width: 100px; background: red; } .right { flex: 1; background: green; } </style> </head> <body> <div class="container"> <div class="left"></div> <div class="right"></div> </div> </body> </html>
知识课堂
先来看两个相关的概念:
●Box: Box是CSS布局的对象和基本单位，一个页面是由很多个Box组成的，这个Box就是我们所说的盒模型。
●Formatting context: 块级上下文格式化，它是页面中的一块渲染区域，并且有一 套渲染规则，它决定了其子元素将如何定位，以及和其他元素的关系和相互作用。
块格式化上下文(Block Formatting Context, BFC) 是Web页面的可视化CSS渲染的一部分，是布局过程中生成块级盒子的区域，也是浮动元素与其他元素的交互限定区域。
通俗来讲: BFC是一 -个独立的布局环境，可以理解为一个容器，在这个容器中按照一定规则进行物品摆放，并且不会影响其它环境中的物品。如果一个元素符合触发BFC的条件，则BFC中的元素布局不受外部影响。
创建BFC的条件:
●根元素: body;
●元素设置浮动: float除none以外的值;
●元素设置绝对定位: position (absolute、 fixed);
●display值为: inline-block、 table-cell、 table-caption、 flex等 ;
●overflow值为: hidden、 auto、 scroll;
BFC的特点:
●垂直方向上，自.上而下排列，和文档流的排列方式-致。
●在BFC中上下相邻的两个容器的margin会重叠
●计算BFC的高度时，需要计算浮动元素的高度
●BFC区域不会与浮动的容器发生重叠
●BFC是独立的容器，容器内部元素不会影响外部元素●每个元素的左margin值和容器的左border相接触
3. 定位+margin
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> <style> * { padding: 0; margin: 0; box-sizing: border-box; } .left { position: absolute; left: 0; width: 100px; height: 300px; background: red; } .right { margin-left: 100px; height: 300px; background: green; } </style> </head> <body> <div class="left"></div> <div class="right"></div> </body> </html>
4. flex 布局
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> <style> .container { display: flex; height: 300px; } .left { width: 100px; background: red; } .right { flex: 1; background: green; } </style> </head> <body> <div class="container"> <div class="left"></div> <div class="right"></div> </div> </body> </html>
5. grid布局
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> <style> .container { display: grid; grid-template-columns: 100px 1fr; box-sizing: border-box; height: 300px; } .left { background: red; } .right { background: green; } </style> </head> <body> <div class="container"> <div class="left"></div> <div class="right"></div> </div> </body> </html>
二、三栏布局的实现
左右定宽，中间自适应
1. float + margin
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <title>CSS实现三栏布局1</title> <style type="text/css"> .left { width: 200px; height: 300px; background-color: #dc698a; float: left; } .middle { height: 300px; background-color: #8cb08b; margin: 0 200px; } .right { width: 200px; height: 300px; background-color: #3eacdd; float: right; } </style> </head> <body> <div class="left">左栏</div> <div class="right">右栏</div> <div class="middle">中间栏</div> </body> </html>
2. float + BFC
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <title>CSS实现三栏布局1</title> <style type="text/css"> .left { width: 200px; height: 300px; background-color: #dc698a; float: left; } .middle { height: 300px; background-color: #8cb08b; overflow: hidden; } .right { width: 200px; height: 300px; background-color: #3eacdd; float: right; } </style> </head> <body> <div class="left">左栏</div> <div class="right">右栏</div> <div class="middle">中间栏</div> </body> </html>
注意：上面两种方法都必须先渲染right,否则right会被middle挤下来
3. 定位 + margin(或者定位+BFC)
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <title>CSS实现三栏布局3</title> <style type="text/css"> .container { position: relative; } .left { width: 200px; height: 300px; background-color: #dc698a; position: absolute; } .middle { height: 300px; background-color: #8cb08b; margin: 0 200px; } .right { position: absolute; right: 0; top: 0; width: 200px; height: 300px; background-color: #3eacdd; } </style> </head> <body> <div class="container"> <div class="left">左栏</div> <div class="middle">中间栏</div> <div class="right">右栏</div> </div> </body> </html>
4. flex布局
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> <style> .container { height: 300px; display: flex; } .left, .right { width: 100px; background: red; } .center { flex: 1; background: green; } </style> </head> <body> <div class="container"> <div class="left"></div> <div class="center"></div> <div class="right"></div> </div> </body> </html>
5. 圣杯布局
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <title>Title</title> <style> .container { height: 200px; overflow: hidden; padding: 0 200px; } .center { width: 100%; height: 200px; background-color: green; float: left; } .left { width: 200px; height: 200px; background-color: blue; float: left; margin-left: -100%; position: relative; left: -200px; } .right { width: 200px; height: 200px; background-color: darkorchid; float: left; margin-left: -200px; position: relative; right: -200px; } </style> </head> <body> <div class="container"> <div class="center"></div> <div class="left"></div> <div class="right"></div> </div> </body> </html>
