What does z-index mean? do?

[color=#0000ff]z-index[/color]Sets the stack order of an elementauto

i don’t understand what this means? stacks what?
silly question i know :stuck_out_tongue:
but thanks

In 3-dimensional graphing (i.e. a 3D graph in Excel), the x-axis is the one that goes across the page; the y-axis is the one that goes up and down the page, and the z-axis is the one that goes “into” the page.

In CSS, you can position 2 or more objects to overlap each other. Their z-indexes determine which objects are “in front of” or “behind” other objects that they overlap. The higher an object’s z-index, the “higher in the stack” of objects it will display.


Briefly :The z-index sets the stacking level (order) of elements on the page. The lower the z-index the further down the stack the element will be. (A stack is just the term for elements on the page and which one is on top of the other one like a stack)

Elements that are positioned on the page are usually displayed in the order that thay are in the html. e.g. the first element will overlap the second element. (assuming of course that areas of the element overlap). By setting the z-index you can control which element is on top and is wholly visible to the viewer.

z-index applies to positioned elements and a parent element that has nested elements will have their z-index controlled by the parent (in relation to other elements outside the nest). Each child element may overlap any other of the child elements according to the z-index set but will only overlap other elements outside the nest if the value of theparent is greater.

I think I’ve just made it sound more complicated than it is



ComputerBob beat me to it (and more eloquently as well:) )

oohh… i think i get it… so basically if i have z-indexed my “column” on the right to be z-index:1 - THEN, when user re-sizes the window and the main & right columns overlap - this will cause the right one to be on top? neat :slight_smile: thanks!