Using CSS to "skin" default prosilver phpBB theme

Hello everybody,

I don't know what I'm doing wrong here, but I've followed the css-tricks [dot] com Screencast #48: Skinning phpBB tutorial video to the letter, yet for some reason it isn't showing what I need it to. Doing anything with code makes my brain want to end itself, so let me know what you need from me because it's crazy important that I get this issue sorted out as it's for work.

In my FTP program I've gone and altered the forum overall_header and overall_footer files with the information from the website header file. I even went and took the piece of code when viewing the page source, and I've deleted/refreshed the cache so many times it's unreal.

Thanks so much in advance!