I can think of a couple of work arounds but in general, printing from browsers is poor.
The first idea would be to use the features of your printer driver to have a narrow margins setting. Some drivers support this.
You could also try overriding the print media CSS for any web page using a browser addin but you are still at the mercy of the browsers print function.
With Firefox, it might be possible to wright a plugin that reset the default print settings - probably overkill but likely possible! :)
Firefox also exposes it's internal CSS, see C:\Program Files\Mozilla Firefox\res I think. So it might be possible to hack the defaults. Not quite what you want though some further hacking using AutoHotKey or some HTA or perhaps a PowerShell script (well actually I'm assuming Windows here but you don't actually say) would give you a fairly easy way to switch. Through truthfully, I'm not sure if you would have to reload the browser after switching.
Sorry, more ideas than answer.