Column 1

This div is smaller than 400px (height) but the min-height property ensures that 400px is reached.

Feel free to copy the source code if you like.

View a 3 column layout

Column 2

This div differs from the first one.

It's height is set to 100% which means

if the content goes more than 400px the div will stretch.

If we left it at 400px any surplus content

would go beyond the div.

I think that if I keep talking

about nothing

in particular then

you will see what i mean

about the div

expanding past 400px.

See what I mean? Good.