#left div: position: relative
Cat image: position: absolute; bottom: 0px; right: 0px;
By setting the position to relative in #left, we have activated its position not to be static. Since we didn’t modify the position (we didn’t change the left, top, etc), the div position didn’t move. However, this will affect the behavior of any contained element that issues an "absolute" position later.
The absolute
position for the image element is now performed with respect to the "div id=left" container - since the #left container has a position that is not set to "static". The div #left defines its height and width, our image is positioned at the bottom of the #left div.