阶段四/Flex实现垂直居中.html

< !DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>flex</title>
    <style>
        .outer {
            width: 300px;
            height: 300px;
            background-color: blue;
            display: flex;
            justify-content: center;
            align-items: center;

        }

        .outer .inner {
            width: 50px;
            height: 50px;
            background-color: #fff;

        }
    </style>
</head>

<body>
    <div class="outer">
        <div class="inner"></div>
    </div>
</body>

</html>