CSS: background: transparent url(/images/menu_background.gif)

[eluser]sawatdee[/eluser]
I am using css for my menu as such:

Code:

.horizontal_menubar
{
    background: #000000 url(/images/menu_background.gif) top left repeat-x;
}

However, my images directory is under my application directory. The following code works, but there is something about having my system directory in my css file that I don't like.

Code:

.horizontal_menubar
{
    background: #000000 url(/system/application/images/menu_background.gif) top left repeat-x;
}

I could also make my css file a php file and reference my images as URLs using site_url (), but that is a little bit of a hassle.

Has anyone else found a more graceful way to do this?