var Xname = ".floatbox";
var menuYloc = null;

$(document).ready(function() {
    try {
        menuYloc = parseInt($(Xname).css("top").substring(0, $(Xname).css("top").indexOf("px")))
    }
    catch (err) {
        menuYloc = 50;
    }

    $(window).scroll(function() {
        var offset = menuYloc + $(document).scrollTop() + "px";
        $(Xname).animate({ top: offset }, { duration: 500, queue: false });
    });
});