Quote Originally Posted by Ryum View Post
The general rule as far as I know, is that a website should be viewable at a 960px width (or viewport). But as said earlier there are different ways of defining width. Percentages are best, but it's hard to design for and make it work across all devices. I always go for the 960px approach, but set this to work as a min-width, so that if a user has a wider screen, margins, padding and so on will adapt to this.
One thing to be careful of is that a 960px screen does not mean you have 960px to play with. For example, a common screen width is now 1920px. A lot of people will have two windows side-by-side, so each window is 960px wide. But that 960px has to include the browser edge/border and the scrollbar – you may only have 940px of actual screen real estate to use. So your carefully crafted site that is exactly 960px wide is now too wide, the edge disappears off the side and your reader has The Dreaded Horizontal Scrollbar.

That's why 960 is a bad width to work to.