floating divs and <br clear=all> problem in ie5 Mac

[Olly]

I am using the following pure css layout with a header and footer:

http://www.fu2k.org/alex/css/layouts...NN4_FMFM.mhtml

The left column floats to the left of the main content (middle
column).

In the middle column I have 3 divs on top of each other, each of which
needs to have a border. To get the borders to display correctly in
Netscape 6 and ie5 (windows) I have to put a <br style="clear:bo th">
before closing each div.

Unfortunately, on ie5 Mac and Safari this causes the 2nd and 2rd div
of the middle column to display below the left coloumn of my layout. I
need the clear:both to get the borders to display correctly on ie5 Mac
too. Are there any other hacks that will force the borders or
backgrounds of a div to expand properly around the contents of the
div?

The middle column divs are coded as below:

<div style="border:1 px solid #000;">
First div contains 3 further float:left divs
<br style="clear:bo th"></div>

<div style="border:1 px solid #000;">
3 further float:left divs
<br style="clear:bo th">
</div>

<div style="border:1 px solid #000;">
contains text
<br style="clear:bo th">
</div>

Thanks,
Olly