1.看看效果吧！
2.html代码index.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
ul{position: relative;padding: 0 -3px;list-style: none;width: 600px;margin: 0 auto}
li{width: 33.33%;position: absolute;box-sizing: border-box;display: block; }
img{width:
