Changing the height of iframe div of parent site

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ASP.NET

Javascript

My scenario is:

ABC.com has an iframe like

<div id="div1" height="1200px">
<iframe id="800px" id="iff1" src="xyz.com/test.aspx"></iframe>
</div>

where ABC.com is my client's site, in which he access my site "xyz.com" in an iframe.
I have tabbed content in my xyz.com/test.aspx

I need to
autosize the iframe from my page (in tabcontent.js)

I tried
parent.window.document.getElementById("msl2Iframe-wrapper").style.height..

it is working in my local, but not in remote (may be cross domain problem).

How can I solve this problem..Please help

Thanks