CSS positioning - faltering steps...

[john_b]

An initial foray into something I've been putting off for years, but I'm going to have to bite the bullet...;-(

I've skirted around CSS for a while and think I've grasped boxes in terms of content, padding, borders and margins but now need to try to connect them somehow for a page with, say, three columns. Nothing fancy: left for navigation, middle for content and right for perhaps a few small images.

I was wondering if there are any general design principles that are reasonably widely accepted? Might it be possible, for example, to specify the left and right column widths in pixels such that you can be pretty sure that any images won't go outside of them and leave the middle column to fill whatever's left?

And how do you do that? Or is it better to use percentages for all three?

In other words, I'd like it to be as flexible as possible to accommodate different screen widths so I'm trying to avoid specifying column widths as completely fixed - am I whistling in the wind?

I'm sure this issue must be old hat to many here so my apologies for that, and also for the somewhat vague nature of the question - I know what I mean...;-)

John