<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>垂直居中</title>
<style>
.container {
position: absolute;
width: 400px;
height: 200px;
background-color: orange;
left: 50%;
top: 50%;
transform: translate(-50%,-50%);
}
</style>
</head>
<body>
<div class="container"></div>