This example is based on “Making the Absolute, Relative” at stopdesign.com. All of the blocks in dashed borders are absolutely positioned.
But their absolute position is relative to the containing block,
#RelativeBlock. It is important that the containing block is “positioned”:
According to the CSS2 spec, an absolute-positioned element is positioned according to its containing block. Any element is considered “positioned” if it has a position value of
fixed(anything other than static). “Static” is one of the possible values for the position property. It’s also the default value for any element if no other position is specified.