Up to 520px width (I think this should cover most smartphones in
portrait mode?):
* the screenshot thumbnails are scaled to full width so they don't
look that left-aligned
* the font size is reduced to 16px instead of 18
The logo scales, there's some (implicit through max-width 92%) padding
on left/right of content, the page itself shouldn'tt have to be scrolled
left/right (code snippets now wrap, tables can be scrolled by themselves
without scrolling the whole site)
