I've been struggling to get Firefox to render text in a sans-serif font. So far, I've only been able to do that by setting the default font as sans-serif. DejaVu Sans Mono and DajaVu Sans are the only other listed fonts that I'm reasonalbly sure are sans-serif. Helvetica and Arial are not there.
sans-serif does work on Konqueror.
Does anyone know how to affect the font-family on Firefox 38.7.0 ?