On Mon, 25 Jul 2016 16:35:44 -0400
Felix Miata <mrmazda@...> wrote:

> Has anyone here figured out if there's some other package that can be 
> installed or some other fix or workaround to avoid this upstream tiny UI 
> fonts bug with trying to use GTK3 builds of Firefox (47+) & SeaMonkey (2.43+) 
> without having to have Gnome3 installed?:
> https://bugzilla.mozilla.org/show_bug.cgi?id=1269274

It seems to pick up system GTK3 settings, which you can override using a text
editor--the theming system is CSS-based.

Find a theme you like, copy its files into ~/.config/gtk-3.0/ , the check the gtk.css 
and/or gtk-widgets.css files for the section containing the defaults for all widgets--
something like this:

    * {
        /* inherit the color from parent by default */
        color: inherit;
        background-color: inherit;
        background-image: none;
        border-image-source: none;
        box-shadow: none;
    }

Add to that section a line that says "font-size:12pt;" (or however large you want it
to be) and see if that helps.  It was picking up the font-face setting I have in my
theme, so related settings *should* work too.

E. Liddell