I'm still playing a lot with (hear "coding on"...) Media Queries in BlueGriffon these days and I ended up trying my own dogfood editing the contents of a famous public web page using Media Queries for responsive design and some @media print stylesheets. Of course, BlueGriffon was not able to show on screen the print stylesheets applied to the document and I found it really sad. So I hacked a little bit (the whole thing is ~10 lines) nsHTMLEditor and nsPresContext to make sure BlueGriffon can show a document in "print" mode in the editable area and of course switch back to the regular screen/all stylesheets. See the result in this youtube video.