Negative white space, adding 55px

I am working with a dashboard panel and I have run into a bug. I have tried a lot to resolve this bug and the only way is by removing this code. Use the middle button of your mouse to scroll down so you can see the bug. The scrollbutton.

$(document).ready(function() {
    $("#NS-02").niceScroll({cursorcolor:"#575961", autohidemode: true, cursorwidth: 8});
    $("#Content").height($(window).height()).width($(window).width()-$("#Left-navigation").width());
    $("#Content").niceScroll({cursorcolor:"#a3a3a3", autohidemode: false});   
});

But If I remove that code my dashboard messes up, hopefully someone knows how to resolve this.

LINK TO THE WEBSITE.

Ok, if I understood what you wanted, the problem is that the #Content div is too high, since you added another div on top. So you could change the line you indicated in this way:

$("#Content").height($(window).height() - $("#Top-navigation").outerHeight(true)).width($(window).width()-$("#Left-navigation").width());

and I think you should also remove the height and width of the Content div from the HTML.