<!DOCTYPE html>
<html lang="en">
<head> <meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>tab</title>
<style>
ul {
display: flex;
position: absolute;
width: 100%;
top: 20px;
left: 50%;
transform: translate(-50%, -50%); }
li {
list-style: none;
position: relative;
padding: 20px;
font-size: 20px;
color: #222;
line-height: 1;
transition: all 0.2S linear;
cursor: pointer;
}
li::before{
content: '';
position: absolute;
top: 0;
left: 100%;
width: 0;
height: 100%;
border-bottom: 2px solid #222;
transition: all 0.2S linear;
}
li:hover::before
{
width: 100%;
top: 0;
left: 0;
transition: 0.2S;
border-bottom: 2px solid #222;
z-index: -1;
}
li:hover~li::before {
left: 0;
}
li:active {
background: #222;
color: #fff;
}
</style>
</head>
<body>
<ul>
<li>首页</li>
<li>分类</li>
<li>样式</li>
<li>效果</li>
<li>游戏</li>
</ul>
</body>
</html>