Ability to fit internal width to iframe width?

I guess this would be a feature request? I would love to somehow change the with to 100%, but from what I can tell, browser disallow injecting CSS into an iframe.

I would like it to go from this:

To this:

I did this by either changing the width to 100% or removing it entirely.

@berkerpeksag - what do you think about this? As long as we provide the default width to the iframe, I think not having a fixed width inside the iframe makes sense.

Also @rb2k - sorry for the late response =)