In your #mainsection add

And that should fix your problem.

Exact a mun-do, but why did this not show up until i set opacity?

Because you have a position of Relative on the mainsection ID. Where as there is no position placed on the nav element.

Z-index is relative to the stacking order. Which means z-index only applies to content of a positioned ancestor. Which is where the relative, absolute and fixed positioning come in.

So basically... lol

Your nav has no positioning, but the box under it does. It is set to relative.

When you set the nav to an opacity it also apply to ANYTHING under it. So you are saying I want the nav to be an opacity of .8 including anything below it so it will now go under something that has a position.

I am not doing a good job of explaining.

But...

There is a simpler way to fix the issue. And that is just by giving your nav a position of relative and a z-index of 1.

Ok, thought about how to explain it better... lol

When you position an element or box or anything you are telling that item to come UP Off the page... When you use relative positioning you are telling the box to come up off the page but stay where it is...

When you position something absolutely you are telling the box to come up off the page and over top everything else.

So... That being said, your maincontent box is position of relative. So it is sitting on top of the page right where the code is sitting.

When you tell something that is still sitting on the page to have an opacity you are then making the item on the page have a lower Z-Index then that of the relative (Up off the page) box.

So, to fix it give the nav a position of relative and a z-index of 1 to say: I want the nav to come up off the page and sit in front of anything that is also up off the page...

Does that make sense to anyone???

Perfect sense.. thanks, I'll adjust things and see what else pops up

Still having a small issue with opera and safari spacing the elements, but made good progress today. The position and z-index combo was exactly the fix i needed.

Did some reorganizing of the site to hopefully please google a little, and managed to make all the menu levels see through with colours.

Fully html5 and css3 with lots of comments to clarify what I'm doing at what point.

Thanks to everyone for your ideas and suggestions