CSS导航栏下划线跟随效果

转载自 https://codepen.io/Chokcoco/pen/PRJvLN
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>CSS导航栏下划线跟随效果</title>
    <style>
    nav {
        100%;
       line-height: 80px;
       background-color: #eee; 
    }
    ul {
        display: flex;
        margin: 0 auto;
        padding: 0;
         60vw;
    }
    li {
        position: relative;
        flex: 1;
        text-align: center;
        font-size: 20px;
        list-style: none; 
        cursor: pointer;   
    }
    /* 借助伪元素 */
    li::before {
        content: '';
        position: absolute;
        top: 0;
        left: 100%;
        /* 刚开始下划线不显示，hover状态下下划线从一侧运动展开 */
         0;
        height: 100%;
        border-bottom: 2px solid #000;
        transition: 0.2s all linear;
    }
    li:hover::before {
         100%;
        left: 0;
        transition-delay: 0.1s;
    }
    li:hover ~ li::before {
        left: 0;
    }

    </style>
</head>
<body>
    <nav>
        <ul>
            <li>关注</li>
            <li>推荐</li>
            <li>排行榜</li>
            <li>视频</li>
            <li>关于我们</li>
        </ul>
    </nav>
</body>
</html>