伪元素实现图片Hover阴影不显示问题排查求助

云上老周

2026-8-12

问题描述

我正在做一个学生项目，要实现可按需修改的数据仪表盘。在弹窗里，我尝试用CSS伪元素给图片加鼠标悬停阴影，但阴影没显示，求排查建议。相关代码如下：

HTML代码

<!DOCTYPE html>
<html>
  <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">
    
    <link rel="stylesheet" href="style.css">
    <link href='https://unpkg.com/boxicons@2.1.4/css/boxicons.min.css' rel='stylesheet'>

    <title>Sail Vision</title>
  </head>
  <body>
      <div class="sidebar">
        <div class="logo_content">
          <div class="logo">
            <i class='bx bx1-c-plus-plus'></i>
            <div class="logo_name">SailVision</div>
          </div>
          <i class='bx bx-menu' id="btn"></i>
        </div>
        <div class="menu-bar">
          <ul class="dash_list">
            <li>
              <a href="#">
                <i class='bx bx-windows'></i>
                <span class="links_name">Dashboard n°1</span>
              </a>
            </li>
            <li>
              <a href="#">
                <i class='bx bx-windows'></i>
                <span class="links_name">Dashboard n°2</span>
              </a>
            </li>
            <li>
              <a href="#">
                <i class='bx bx-windows'></i>
                <span class="links_name">Dashboard n°3</span>
              </a>
            </li>
            <li>
              <a href="#">
                <i class='bx bx-customize modal-trigger'></i>
                <span class="links_name">Template</span>
              </a>
            </li>
          </ul>
          <div class="bottom_content">
              <li>
                <a href="#">
                  <i class='bx bx-cog'></i>
                  <span class="links_name">Paramètre</span>
                </a>
              </li>
          </div>
        </div>
      </div>
      <div class="home">
        <div class="template-1">Template n°1</div>
      </div>
      <div class="modal-container">
        <div class="overlay">
          <div class="template">
            <div class="popup-header">
              <button class="close-modal modal-trigger">X</button>
              <h1>Choix des templates</h1>
            </div>
            <div class="popup-body">
              <ul class="temp-list">
                <li>
                  <a href="#">
                    <img src="Template1.png" alt="t1">
                  </a>
                </li>
                <li>
                  <a href="#">
                    <img src="Template1.png" alt="t1">
                  </a>
                </li>
                <li>
                  <a href="#">
                    <img src="Template1.png" alt="t1">
                  </a>
                </li>
              </ul>
            </div>
          </div> 
        </div>
      </div>
      <script src="script.js"></script>
  </body>
</html>

CSS代码

@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@300;400;500;600;700&display=swap');

*{
    font-family: 'Poppins', sans-serif;
    margin: 0;
    padding: 0;
    box-sizing: border-box
}

:root{
    --body-color: #E4E9F7;
    --sidebar-color: #FFF;
    --primary-color: #1c1a1a;
    --primary-color-light: #F6F5FF;
    --toggle-color: #DDD;
    --text-color: #707070;

    --tran-02: all 0.2s ease;
    --tran-03: all 0.3s ease;
    --tran-04: all 0.4s ease;
    --tran-05: all 0.5s ease;
}

body{
    height: 100vh;
    background: var(--body-color);
}

.sidebar{
    position: fixed;
    top: 0;
    left: 0;
    height:100%;
    width: 78px;
    background: var(--primary-color);
    padding: 6px 14px;
    transition: all 0.5s ease;
}

.sidebar.active{
    width: 240px
}

.sidebar .logo_content .logo{
    color: #FFF;
    display: flex;
    height: 50px;
    width:100%;
    align-items: center;
    opacity: 0;
    pointer-events: none;
}

.sidebar.active .logo_content .logo{
    opacity: 1;
    pointer-events: none;
}

.logo_content .logo i{
   font-size: 28px;
   margin-right: 5px;
}

.logo_content .logo .logo_name{
    font-size: 20px;
    font-weight: 400;
}

.sidebar #btn{
    position: absolute;
    color: #FFF;
    top: 6px;
    left: 50%;
    font-size: 20px;
    height: 50px;
    width: 50px;
    text-align: center;
    line-height: 50px;
    cursor: pointer;
    transform: translateX(-50%);
}

.sidebar.active #btn{
    left:90%;
}

.sidebar ul{
    margin-top: 20px;
}

.sidebar li{
    position: relative;
    height: 50px;
    width: 100%;
    margin: 0 0px;
    list-style: none;
    line-height:50px ;
}

.sidebar li a{
    color: #FFF;
    display: flex;
    align-items: center;
    text-decoration: none;
    transition: all 0.4s ease;
    border-radius: 12px;
    white-space: nowrap;
}

.sidebar li a:hover{
    color: #11101d;
    background: #FFF;
}

.sidebar li a i{
    height: 50px;
    min-width: 50px;
    border-radius: 12px;
    line-height: 50px;
    text-align: center;
}

.sidebar .links_name{
    opacity: 0;
    pointer-events: none;
}

.sidebar.active .links_name{
    opacity: 1;
    pointer-events: auto;
}

.sidebar .menu-bar{
    height: calc(100% - 50px);
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.home{
    position: relative;
    height: 100vh;
    left: 78px;
    width: calc(100% - 78px);
    background: var(--body-color);
    transition: var(--tran-05);
}

.home .text{
    font-size: 30px;
    font-weight: 500;
    color: var(--text-color);
    padding: 8px 40px;
}

.sidebar.active ~ .home{
    left: 240px;
    width: calc(100% - 78px);
}

.modal-container{
    display: none;
    position: fixed;
    top: 0;
    width: 100vw;
    height: 100vh;
    flex-direction: column;
}

.modal-container.active{
    display: flex;
}

.overlay{
    position: absolute;
    width: 100%;
    height: 100%;
    background: #333333d3;
}

.template{
    position: fixed;
    left: 50%;
    top: 50%;
    transform: translate(-50%,-50%);
    height: 300px;
    max-height: 720px;
    min-width: 520px;
    width: 45%;
    display: flex;
    flex-direction: column;
}

.popup-header{
    width: 100%;
    height: 8.5%;
    border-radius: 2px;
    align-items: center;
    justify-content: space-between;
    padding: 0% 2%;
    background-color: #FFF;
    color: rgb(0, 0, 0);
}

.close-modal{
    padding: 5px 20px;
    border: none;
    border-radius: 2px;
    font-size: 10px;
    position: absolute;
    top: 0px;
    right: 0px;
    cursor: pointer;
    background: #fff;
    color: rgb(0, 0, 0);
}

.close-modal:hover{
    color: #FFF;
    background: rgb(188, 15, 15);
}

.popup-header h1{
    font-size: 12px;
    margin-top: 5px;
    margin-left: 0px;
    font-family: Montserrat, sans-serif;
    font-weight: 500;
}

.popup-body{
    height: 80%;
    padding: 2%;
    overflow-y: auto;
    background-color: #e0e0e0;
}

.modal-container .popup-body ul{
    list-style: none;
    position: relative;
    height: 50px;
    width: 100%;
    margin: 0 10px;
    list-style: none;
    column-width: 200px;
}

.modal-container .popup-body ul li a img{
    padding: 10px 10px;
    width: 175px;
    border-radius: 8px;
    background: #fff;
    cursor: pointer;
    box-shadow: 0 0 7px rgba(18,18,18,0.5);
}

.modal-container .popup-body ul li a img::after {
    content: "";
    display: block;
    width: 100%;
    height: 100%;
    box-shadow: 0 0 25px rgba(18,18,18,0.8);
    opacity: 0;
    transition: opacity 0.3s ease-out;
    z-index: 1;
}

.modal-container .popup-body ul li a img:hover::after {
    opacity: 1;
}

JS代码

const body = document.querySelector("body"),
    sidebar = body.querySelector(".sidebar"),
    btn = body.querySelector("#btn");

btn.addEventListener("click", () =>{
    sidebar.classList.toggle("active");
})

const modalContainer = document.querySelector(".modal-container");
const modalTriggers = document.querySelectorAll(".modal-trigger");
modalTriggers.forEach(trigger => trigger.addEventListener("click",toggleModal))

function toggleModal(){
    modalContainer.classList.toggle("active")
}

错误原因排查

img标签不支持伪元素：<img>属于HTML替换元素，浏览器规范不允许为这类元素生成::before/::after伪元素，这是阴影不显示的核心原因。
伪元素定位缺失：即使忽略规范问题，你的伪元素没有设置position: absolute，会和原图重叠且无法正确覆盖，z-index也无法发挥预期作用。

修复方案

方案1：用容器伪元素实现阴影（保留原有思路）

给每个图片套一个容器，通过容器的伪元素实现悬停阴影：

<!-- 修改HTML，给img加容器 -->
<li>
  <a href="#">
    <div class="img-wrapper">
      <img src="Template1.png" alt="t1">
    </div>
  </a>
</li>

/* 修改CSS，用容器伪元素实现阴影 */
.modal-container .popup-body ul li a .img-wrapper {
  position: relative;
  display: inline-block;
}

.modal-container .popup-body ul li a .img-wrapper::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border-radius: 8px;
  box-shadow: 0 0 25px rgba(18,18,18,0.8);
  opacity: 0;
  transition: opacity 0.3s ease-out;
  z-index: 1;
  pointer-events: none;
}

.modal-container .popup-body ul li a .img-wrapper:hover::after {
  opacity: 1;
}

方案2：直接给图片加hover阴影（更简洁）

不需要伪元素，直接修改图片的hover样式：

.modal-container .popup-body ul li a img:hover {
  box-shadow: 0 0 25px rgba(18,18,18,0.8);
  transition: box-shadow 0.3s ease-out;
}

内容的提问来源于stack exchange，提问作者Seji

伪元素实现图片Hover阴影不显示问题排查求助

HTML代码 #

CSS代码 #

JS代码 #

方案1：用容器伪元素实现阴影（保留原有思路） #

方案2：直接给图片加hover阴影（更简洁） #

HTML代码

CSS代码

JS代码

方案1：用容器伪元素实现阴影（保留原有思路）

方案2：直接给图片加hover阴影（更简洁）