Css overlaping divs!

Hi…
i’m just starting put with css and stumbled upon a problem:

i have 2 divs on my main page, one that is set to float right, and the other is fixed to the left of the screed, and has a defined width. the problem is that if i resize my browser too much, the div that floats to the righ just overlaps with the other div. what i want to do is that if you resize the browser until the 2 divs meet, the floated one does’t overlap, but it stops right near the edge of the other one.
can anyone help me with this?

thanks

give the one to the right a margin-left equal to the width of the div on the left. That way you dont have to float