modifying iframe source

Dear all,

Currently I am struggling with the following; I am building an app in with external sites are reviewed by humans. The reviewing focusses on certain link which I want to highlight. In the past I could just present the site and be done with it. This I did with an IFRAME. However now I need to modify the source of the external website. That is all anchor tags with a specific text need to be highlighted, which I did with 'style="background-color=yellow;".

Unfortunately the iframe approach no longer works. Just outputting the modified external site content did not make Rails happy either. I am exploring the option of writing the modified content to disk and then refer to it in the 'src' clause of the iframe tag. But so far no love. Rails appears to interpret this as an action... So my question is; Is there a way in which Rails does not do this and I can link (aka src) to a file on disk? Or should I approach this problem different altogether?

Any help is greatly appreciated,

With kind regards, Harm