I tend to make my pages a fairly narrow width (and centered) unless there is something necessary pushing it wider. That way, the text line length will never make things hard to read. Generally about 50 characters is a comfortable maximum. I shrunk yours to 800px and it should look good even on a smaller screen.
Be careful about assigning pixel size to a font. In some browsers, when someone "zooms" the page, the font doesn't change. Use an EM size instead.
CSS formatting and divisions are the (present and) future of page design. Tables, while convenient, have their limitations and cannot be globally changed.
(One of my other volunteer jobs is being a moderator
here.)