The focus is in the #mainbox layer nested # Menu, # sidebar and #content three layers. When #Content's content increases, # Content will increase, and the height of #mainbox will also be opened, and the # Footer layer is automatically moved. This achieves a high degree of adaptation.
Also worth noting is: #menu and #Content are floating on the right side of the page "float: right;", # sidebar is floating on the left "float: left;", this is a floating method, but also Absolute positioning to achieve this effect.
There is another problem with this method, that is, the background of the side #sidebar cannot be 100%. The general solution is to fill in the background color of the body. (You can't use the background color of #mainbox, because the background color of #mainbox in the browser such as Mozilla is invalid.)
Source: Web Designer