I have an iframe:
If something.html from externaldomain.com has the css:
As a workaround, if all else fails, you can download the contents of something.html using server-side logic, like ASP.NET or PHP, and save it on your local web-server somewhere. Then you can avoid the same-origin policy, or you can even modify the HTML/CSS yourself on the server, for ex., remove the offending position:relative.