Import ASP file and CSS

So I'm building a site and have a menu running down the side of the page. I had it just coded into the site originally, but after looking at it for a bit, decided to move it into a seperate file and just include incase I need to update the menu later.

But now that I've moved the menu over to it's own file (menu.asp) and use an include statement to include the file, my CSS definitions are no longer working.

Any suggestions or ideas?

Thanks!