Using flex layout and overflow to realize different problems on chrome and firefox

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        html, body {
            height: 100%;
            width: 100%;
            box-sizing: border-box;
        }

        .root {
            height: 100%;
            background: -sharp123456;
            display: flex;
            flex-direction: column;
        }

        .header, .footer {
            flex: 0 0 50px;
            border: 5px dashed red;
        }

        .body {
            display: flex;
            flex: 1;
        }

        .center {
            flex: 1;
            border: 5px dashed gold;
            overflow: auto;
        }

        .content {
            height: 1000px;
            border: 5px dashed cornflowerblue;
        }

        .left {
            flex: 0 0 300px;
            border: 5px dashed greenyellow;
        }

    </style>
</head>
<body style="margin:0">
<div class="root">
    <div class="header">header</div>
    <dvi class="body">
        <div class="left">
            left
        </div>
        <div class="center">
            <div class="content">
            </div>
        </div>
    </dvi>
    <div class="footer">footer</div>
</div>
</div>
</body>
</html>

when I use flex to lay out the Grail, content sets the height, and when the parent sets overflow: auto , chrome becomes normal, but firefox will push the height out, as shown in the following figure