CSS Positioning, Vertically & Horizontally centering a DIV?

I am trying to create a page, where there is a div in the middle of the page centered horizontally, not vertically, with 3 more divs inside of it which are centered vertically and horizontally with equal spacing. In order to achieve this I thought it would be best to create another div with no background colour, then using margin: auto on it, this div is centered in the main div, but I can't get the 3 other divs to center in that, it's like the margins aren't taking into account the parent element?I am trying to create a page, where there is a