bottom
This property defines the y (vertical) coordinate for a positioned element, relative to the bottom of the enclosing element or browser window. Values can be specified as lengths (inches, pixels, and so on), as a percentage of the containing object's dimensions, or as auto, which lets this property function as determined by the browser or as defined by the parent element.
Examples
#div1 {position: absolute; left: 100px; bottom: 150px;}
#div2 {position: absolute; left: 50%; bottom: 30%;}
#div3 {position: absolute; left: auto; bottom: auto;}
Browser and CSS Support Notes
CSS2
IE 5, 5.5, 6
Nav 6, 7
Opera 5, 6, 7