<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>布局</title> <style> header{ height: 100px; background-color: #cccccc; } section{ background-color: #FF7100; height: 400px; } #child1{ width: 10%; height: 100%; background-color: #FF0000; float: left; /*padding-left: 1px;*/ border: 10px solid black; /*margin border padding都会影响页面布局,content不变, 实际宽度为:在content的基础上加上margin border或padding*/ /*变态盒模型 borber-box 添加padding或者border不会影响页面布局 只会挤压页面内容content*/ box-sizing: border-box; /*overflow规定了内容溢出盒子时如何处理*/ overflow: auto; /*border-radius 盒子弧度*/ border-radius: 50%; } #child2{ width: 80%; height: 100%; background-color: aqua; float: left; border-radius: 50%; } #child3{ width: 10%; height: 100%; background-color: brown; float: left; border: 10px solid black; box-sizing: border-box; border-radius: 50%; } </style> </head> <body> <header></header> <section> <div id="child1"></div> <div id="child2"></div> <div id="child3"></div> </section> </body> </html>