24hrs format for html inputs in Firefox

My system language on my linux machine is set to English, but as a German raised with 24-hour days, I simply cannot wrap my head around to get the 12-hours am/pm format intuitively. By the time I learned that am is in the morning and pm is in the evening. But when it comes to 12:00 as the mid of the day and 0:00 in the night, I’m lost.

Of course I have already set the time format to 24-hours in my system settings (Ubuntu Date & Time > Time Format set to 24-hour), but Firefox still uses the 12-hours format for html inputs with type="time".

As a solution you open about:config and set intl.regional_prefs.use_os_locales to true. Now simple <input type="time"> will use the 24h format!