div页面底部对齐[提取修改]

    <script language="javascript" type="text/javascript">
        function $()
        {
            return document.getElementById?document.getElementById(arguments[0]):eval(arguments[0]);
        }
        var Sys = {};
        var ua = navigator.userAgent.toLowerCase();
        if (window.ActiveXObject)
            Sys.ie = ua.match(/msie ([\d.]+)/)[1]
        else if (document.getBoxObjectFor)
            Sys.firefox = ua.match(/firefox\/([\d.]+)/)[1]
        else if (window.MessageEvent && !document.getBoxObjectFor)
            Sys.chrome = ua.match(/chrome\/([\d.]+)/)[1]
        else if (window.opera)
            Sys.opera = ua.match(/opera.([\d.]+)/)[1]
        else if (window.openDatabase)
            Sys.safari = ua.match(/version\/([\d.]+)/)[1];
    
        function getClientBounds()
        {
            var clientWidth;
            var clientHeight;
           
            if (Sys.ie)
            {
                clientWidth = document.body.clientWidth;
                clientHeight = document.body.clientHeight;
            }
            else if (Sys.safari)
            {
                clientWidth = window.innerWidth;
                clientHeight = window.innerHeight;
            }
            else if (Sys.opera )
            {
                clientWidth = Math.min(window.innerWidth, document.body.clientWidth);
                clientHeight = Math.min(window.innerHeight, document.body.clientHeight);
            }
            else
            {
                clientWidth = Math.min(window.innerWidth, document.documentElement.clientWidth);
                clientHeight = Math.min(window.innerHeight, document.documentElement.clientHeight);
            }
 
            return { width : clientWidth, height : clientHeight };
        }
 
        function resetLiveMessengerPosition()
        {
            var clientBounds = getClientBounds();
            var container = document.getElementById("liveMessengerContainer");
           
            var scrollLeft = (document.documentElement.scrollLeft ?
                    document.documentElement.scrollLeft : document.body.scrollLeft);
            var scrollTop = (document.documentElement.scrollTop ?
                    document.documentElement.scrollTop : document.body.scrollTop);
                   
            var containerLeft = scrollLeft + clientBounds.width - container.clientWidth - 5;
            var containerTop = scrollTop + clientBounds.height - container.clientHeight;
                   
            $("liveMessengerContainer").style.top=containerTop + "px";
            $("liveMessengerContainer").style.left=containerLeft + "px";
        }
       
        window.onscroll=function(){resetLiveMessengerPosition();};
        window.onresize=function(){ resetLiveMessengerPosition();};
        window.onload=function(){ resetLiveMessengerPosition();};
    </script>