<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>3.基本选择器</title> <style type="text/css"> ul{ padding: 0; margin: 0; width: 450px; border: 1px dashed #666; padding: 10px 5px; } ul:after{ content:''; display:block; clear: both; } li{ list-style: none; float: left; width: 40px; line-height: 40px; text-align: center; border-radius: 30%; background-color: skyblue; margin-right: 5px; } #item1{ background-color: lightgreen; } .green{ background-color: red; } ul li{ color: white; } ul *{ /*border: 1px solid black;*/ } ul>li{ background-color: blue; } #item2+li{ background-color: black; } #item2 ~ li{ background-color: black; } </style> </head> <body> <ul> <li id="item1">1</li> <li>2<li> <li>3</li> <li>4</li> <li>5</li> <li id="item2">6</li> <li>7</li> <li>8</li> <li>9</li> <li>10</li> </ul> </body> </html>