I want to be able to create a pop up success message in the center of the screen AND with z-index greater than all the other elements, so that it appears in front of them. However all html elements in my page have style display:static; (content div, header, sidebar,etc..) so is it still possible to do so ?
Thanks a lot.
If all elements are statically positioned, than yes, the pop-up message will always show up on top. Static elements have a 0 z-index by default, so setting anything with a higher z-index and position:[relative, absolute, fixed] will place it on top.
Read more here and css-tricks has a great overview/tutorial of z-index. http://css-tricks.com/almanac/properties/z/z-index/