<!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>Document</title> <style> .modal_cover{ display: none; 100%; height: 100%; position: fixed; top: 0; left: 0; background-color: rgba(0, 0, 0, .6); } .modal{ position: absolute; 823px; background: white; z-index: 99; height: 80px; /* 水平垂直居中 */ left: 50%; top: 50%; transform: translate(-50%,-50%); /* 超出高度右侧出现垂直滚动条 */ overflow:auto; overflow-x:hidden; } .button{ margin: 40px; } </style> </head> <body> <div class="modal_cover" style="display:block"> <div class="modal"> <button class="button">提交申诉</button> </div> </div> </body> </html>