Comment 11 for bug 1824260

CourierStd is not defined in any of the config files at `/etc/fonts/conf.d`, so it falls back to sans-serif, not monospace. On my computer, the sans-serif fallback is set to Ubuntu.

In config files at `/etc/fonts/conf.d`, creating duplicate rules for "CourierStd" each time "Courier" or "Courier New" is mentioned should fix the problem.

On my computer, `grep -Rl Courier` lists the following files:

    30-metric-aliases.conf
    45-latin.conf
    60-latin.conf

Using `apt-file search`, the package those files belong to is `fontconfig-config`.