W3School TIY Editor
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<!DOCTYPE html> <html> <head> <meta name="viewport" content="width=device-width, initial-scale=1"> <style> .container { position: relative; width: 50%; } .image { display: block; width: 100%; height: auto; } .overlay { position: absolute; top: 0; bottom: 0; left: 0; right: 0; height: 100%; width: 100%; opacity: 0; transition: .5s ease; background-color: #008CBA; } .container:hover .overlay { opacity: 1; } .text { color: white; font-size: 20px; position: absolute; top: 50%; left: 50%; -webkit-transform: translate(-50%, -50%); -ms-transform: translate(-50%, -50%); transform: translate(-50%, -50%); text-align: center; } </style> </head> <body> <h2>渐显覆盖层</h2> <p>将鼠标悬停在图像上以查看效果。</p> <div class="container"> <img src="/i/pic/avatar-1.png" alt="Avatar" class="image"> <div class="overlay"> <div class="text">Hello World</div> </div> </div> </body> </html>