<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>css设置遮罩</title> <style> .box::before { content: ""; position: fixed; top: 0; right: 0; bottom: 0; left: 0; z-index: 2; background-color: #000; opacity: .3; } #main{ width: 500px; height: 500px; position: fixed; top: 50%; left: 50%; margin-top: -250px; margin-left: -250px; background: #fff; z-index: 2; border-radius: 10px; } </style> </head> <body> <div class="box"> <div class="bg"></div> <div id="main"> </div> </div> </body> </html>
