and this is a complication that must be taken into account. z-index The actual number assigned to a particular place in the Z-order is sometimes known as the z-index. In particular the CSS property that sets the stack order of specific elements is known as the z-index. An element with greater stack order is always in front of another element with lower stack order. p { position: relative; z-index: -1; } Negative stack orders can also be used in the same manner. A negative value will appear behind a positive one. z-index only works on elements that have a position value (e.g. position: relative;) and for many coders, this one of the first things to investigate when debugging why the z-index isn't working. Like all other CSS properties, it can be set with JavaScript as well with the following syntax: object.style.zIndex= '1'; See also Z-buffer References Computer graphics