ashgilpincom,
I have just had a look at your site and it seems to have a lot of hardcoded styles. Where possible you should attach and ID or Class to your div's and implement the style using your CSS. There is also a lot of Javascript code in the page, this would be better being sat in external JS files and just linked to. This helps when spiders traul your site, many have a limit to how much info they scan, so if they have to search through loads of JS at the top of the page they may never get to reading the actual information on the site.
Sorry for the rant but you seem to have implemented some good pieces of CSS and followed them up with some poor bits. As a final point you also seem to have put your nav's in as Definition Lists (DL) and Definition Titles (DT) but I would advise you to use Unordered Lists (UL) and List Item (LI) instead. DL's should be used for information and their definitions. So definition lists should have <dl>, then definition title <dt>, then definition description <dd>.
Apologies again, if you have any questions I am pretty CSS savy, I've spent the last two years building sites using it everyday.