<!DOCTYPE html><html lang="zh-CN"> <head> <meta charset="UTF-8" /> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> </head> <body> <header style="display: flex; place-items: center"> <h1 style="margin-right: auto">后台管理<small>v1.0</small></h1> <section style="margin-left: auto"> <em>admin</em> <button onclick="location.href='logout.php'">退出</button> </section> </header> <nav> <a href="demo.html" target="content">课程表</a> <a href="demo1.html" target="content">注册表单</a> <a href="demo3.html" target="content">视频与音频</a> <a href="demo4.html" target="content">导航</a> </nav> <iframe src="default.html" name="content" width="800px" height="500px" ></iframe> <div> <!-- ? 1. 标签选择器 <h2> --> <h2>Hello world</h2> <style> h2 { color: #099; } </style> <!-- ? 2. 属性选择器 title --> <h2 title="php.cn老师">Hello, 朱老师</h2> <style> h2[title] { color: #019; } </style> <!-- ? id,class: 是属性,但是它也是高频属性,css为它设计了语法糖 --> <h2 id="active">Hello, php中文网</h2> <h2 class="hello">Hello, php.cn</h2> <style> h2#active { color: #030; } h2.hello { color: brown; } </style> <!-- ? 群组选择器, 多个选择器之间用逗号分开 --> <h5>合肥</h5> <h3>南京</h3> <h4>杭州</h4> <style> h5, h3, h4 { color: #070; } </style> </div> </body></html>
