Firefox and element opacity

Hi.

I have a site that I am developing that has a slider underneath a header and menu block that I have used negative margin on to align it to the top of the site, so by overlapping the header and menu.

For this header and menu I have used some slight opacity so that it is is visible over this slider.

Works beautifully in Chrome but in Firefox not only does the slider physically ignore the negative margin and drop below the header and menu but the opacity rules for the header and menu are also ignored.

Anyone ever had this problem before?

I’ve managed to rectify this.

I had to give the slider an absolute position to the top of the site and Firefox liked it.