Resize A Page Dependant On The Content Of An Iframe?

Ive written some code to try and resize a page dependant on the content oof an iframe. Code is as follows:

window.onload=sizeAdj();
function sizeAdj() {
var elFrame = document.getElementById('theFrame');
var elTable = document.getElementById('tableGrab');
var elDivMain = document.getElementById('main');
var elDivWrapper = document.getElementById('wrapper');
[Code]....

I originally thought that I would just be able to resize the iframe and the other elements would follow suit but as you can see Ive tried to resize the other encasing elements also. The code resizes partially in chrome but only to a certain point and not to the full height of the doc content.