如何如何做到加定位实现输入的内容不被过渡的小i覆盖

z-index要和定位连用但是当我加相对定位和绝对定位的时候某些效果又消失了求解？

img


html>
<html lang="en">
<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>Documenttitle>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        .input_Box {
            position: relative;
            width: 400px;
            margin: 100px auto 0;
            background-color: aqua;
        }
        .input_Box input {
            border: 0;
            width: 100px;
            height: 30px;
            outline: none;
            z-index: 9;
        }
        i {
            position: absolute;
            left: 0;
            bottom: 0;
            width: 100px;
            height: 1px;
            background-color: aqua;
            transition: 0.6s;
            
        }
        input:focus~i {
            position: absolute;
            height: 30px;
            z-index: 1;
        }
    style>
head>
<body>
    <div class="input_Box">
        <input type="text">
        <i>i>
    div>
    
body>
html>

img


我看了半天没明白你要实现什么效果？
私聊吧