Element's CSS, reverts back at the end of page load?

(roblox banner element, trying to make it not float) to relative using Greasemonkey, with all privileges enabled. But, every time, at the end of the loading of the document, it reverts to floating.

I even tried appending bannercentercontainer to a different element, but I don't know if I did it right... can you please help me change this to relative position?

I tried:

$('#Banner').css('position', 'relative !important') and

if ($('#Banner').css('position') == 'fixed') { $('#Banner').css('position', 'relative') } , but it just changed back once the page finished loading.