Thanks for that Jacob. Firefox is one of the browsers that my website works OK with. It's Explorer and Opera that I have problems with.

I have solved the problem with the mystery blue boxes. They were simply borders. I had not specified any borders and just left the border value blank, but Firefox decided to use a default and put in ugly blue boxes. I have now entered a '0' value for borders and it looks fine.

I still have the problem with certain things not opening in the 2 browsers mentioned.

Thanks again.