I started to develop my own webdesign using an grid framework 960 CSS Framework and also noticed that most of other famous css grid frameworks use 940/960px as maximum page width? Some of them have an online generators where you can calculate and generate the same framework but for different width size.
Can you tell me why they suggest 960 px as default?
And more important: Why everything is measured in pixels rather than pt, cm, % or any other css units?
Edit: Isn't it better to use 'in' as css unit and be sure that on every screen (computer, smartphone) it will have the same size?
P.S. Some other grid css frameworks: