<head>
<style>
.adModal{
position:fixed;
background: black;
top: 0;
right: 0;
bottom: 0;
left: 0;
z-index: 998;
opacity: 0.4;
}
.tdModal{
position:fixed;
background: white;
z-index:1000;
width: 400px;
height: 300px;
left: 50%;
top: 50%;
margin: -200px 0 0 -300px;
}
</style>
</head>
<body>
<div class="adModal"></div>
<div class="tdModal">
<p>
姓名：<input type="text" name="name">
</p>
<input type="button" value="提交">
</div>
</body>
原文：https://www.cnblogs.com/jmc218/p/13336391.html