Question Resizing of Web Page Height

[xiecsuk]

I have a site which has a full width fixed height header and a full width fixed height footer. In between I have a fixed width left hand column, a fluid middle column and a fixed width right hand column. Everything displays OK when I open the page.
If I then reduce the width of the page, and the centre column has a lot of text, the text disappears under the footer because the height of the page is not being recalculated. If I then refresh the page everything is OK at the new width.
How do I get the height automatically adjusted to the new page width?
xiecsuk