The pink really, honestly, wouldn't be so bad as a background and across the entire header. But there should be a different background for the text areas.
I know you mentioned your site was created to meet the needs of your team first, but I hope you come away from this thread with at least some of our suggestions. One that I view as important whether it's an intranet for a Fortune 500 company or a team's public website, is to have common navigation throughout the entire site. It doesn't even have to look the same (although that's strongly encouraged), you just need
something somewhere on the page so that people can navigate between pages.
It doesn't look like you're using PHP or any other scripting language, so I guess you could try the suggestion here, although it'll only work if your web server was configured to support it:
http://webdesign.about.com/od/ssi/a/aa052002a.htm
Essentially, you'd make a file "header.html" and just include it at the top of each page.