Question

Look at the stackoverflow site – the screen adjusts width by decreasing the margins, until there are no margins, when the site becomes fixed. How can this be done?

Answer 1

The page is just centered, I believe. I would just contain all elements on the page with one div tag with a fixed width (of say 800px). Then, I would center it with margin: 0 auto;

#all {
    width: 800px;
    margin: 0 auto;
}