jQuery Forum

I'm a graphic design student working on a summer project, and dabbling into some web design. I've created a mock up of an ebay sister site and I'm nearly finished but completely stuck in a rut with one thing that is so frustrating, I don't even know is possible.

I have a large Menu Navigation system which includes sub menus. My First button, (Categories) has a sub menu which consists of 'Fashion', 'Motors', 'Property' & 'Services' divs, which are set to hide as default but fade in once clicked.

The Problem I have is the 'Categories' Button has an opacity toggle on it, so when you click it the homepage div fades to 50% and the sub menu fades in. When you go through the Sub menu and for example click 'Motors' the homepage div fades out, and the motors div fades in. 

When I click on the 'Categories' button again this fades the 'Motors' div out and fades the homepage div back in, but the Homepage is back at 100% because I have the opacity toggle on it. I need the homepage to stay at 50% whenever the Sub menu is fade in, can this be triggered by the sub menu div on fade in? or even the Motors div fade out?

I must also mentioned that my other Navigation buttons toggle the homepage opacity same as the Categories button.