Transparent menu with slider underneath

Hi there,

I have seen on several sites where their menu/header will be semi-transparent and overlap the top of a slider (so in this case, the revolution slider). It looks like of like what the sticky menu looks like when you scroll down the page.

Can you give me an idea of the css or what setting i might have to change to do this? it seems like 2 things: 1) make the background transparent and 2, make it overlay.

Thanks in advance. Great theme.

K