"Ratios are at the core of any well designed grid system. Sometimes those ratios are rational, such as 1:2 or 2:3, others are irrational such as the 1:1.414 (the proportion of A4). "

CSS framework - "The 960 Grid System is an effort to streamline web development workflow by providing commonly used dimensions, based on a width of 960 pixels. There are two variants: 12 and 16 columns, which can be used separately or in tandem. Read more."