We currently query Qt for system fonts using QFont::setStyleHint(). The
docs from Qt have the following note regarding this API on X11:
Qt does not support style hints on X11 since this information is not
provided by the window system.
This prevents any monospace font from working on X11 systems. For now,
work around this by specifying the font-family for fonts which Qt has
listed as mapping to a CSS generic font-family.
This makes vector fonts load on macOS, where /usr/share/fonts doesn't
exist and Ladybird would only load the bitmap fonts from ./res/fonts
in the SerenityOS resource root directory.
Additionally, fonts in {/usr/share/local,~/.local}/fonts are now loaded
on Linux.