html viewport的学习

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1.0, maximum-scale=1">
    <title>width</title>
    <style>
        body {
            padding:0;
            margin:0;
        }
        .container {
            margin: 0;
            padding: 0;
            background-color: red;
        }

       /*  @media all and (max-device-width: 320px) {
           .container {
               width: 100px;
           }
       } */
    </style>
</head>
<body>
    <div class="container" id="container">
        hello world
    </div>
    <script>
        alert("window.innerWidth = " + window.innerWidth);
        alert("screen.width = " + screen.width);
        alert("container = " + document.getElementById('container').clientWidth);
    </script>
</body>
</html>

演示地址
http://xhope.top/samples/html/viewport.html