finally found a reliable solution for the expanding main div in css layout, add the following line to the main Content div css...
overflow:auto;
then had a strange effect in Explorer where links would wrap when a pop-up menu disappeared. After another search and stripping the page apart (again!), solution is to add a footer div at the very end of the main contaier (the thing described above) and add this to the css...
#mainFooter {
clear: both;
}
Whilst I'm here - to centralise the content and still allow absolute positioning of layers, I used this one as the 'master' div tag:
div style="margin: 10px auto; background:#EEEEEE; position: relative; width: 930px;"
