<meta id='viewport' name="viewport" content="width=480, height=640,initial-scale=1, maximum-scale=1, user-scalable=no" />

<script>

    //Get meta tag
    var meta = document.getElementById('viewport');

    var scaleAmount = 1;
    var width = window.outerWidth;
    var height = window.outerHeight;

    if(window.outerWidth > window.outerHeight)
    {
        width = window.outerHeight;
        height = window.outerWidth;
    }

    var border = 1;
    var windowWidth = width - (border * 2);
    var windowHeight = height - (border * 2);

    var widthRatio = windowWidth / 480;
    var heightRatio = windowHeight / 640;

    if(widthRatio < heightRatio)
    {
        scaleAmount = widthRatio;
    }
    else
    {
        scaleAmount = heightRatio;
    }

    meta.setAttribute('content','width=480,height=640,initial-scale='+scaleAmount+', maximum-scale='+scaleAmount+', user-scalable=no');



</script>