Oh man, making a 7-segment display was my favorite question to ask frontend developers. Eventually turning it into a real clock if they were fast enough. Captures lots of basic CSS positioning, JS timers behavior and general ideas like breaking things into components etc

Man where were you at when I was getting asked questions "to see if you've prepared for the interview" with leet code for damned UI frontend positions... I loved answering your type of questions and most companies would not do this for some reason.

I'm guessing when you say "ask frontend developers" you mean "at job interviews". But I like to think you mean something like "at cocktail parties" or other social situations.

I'm choosing to imagine a bomb-defusal movie scene, where the protagonist must correct the layout of the countdown timer to save the day.

I've been looking for something exactly like this, actually! I'm making a hardware device that is a habit tracker, and the screen will be a few 7 segment displays. Being able to simulate the displays like this is very nice. Also very cool that it displays whatever you type in!

Is there any physical hardware that uses the same segmentation scheme?

Edit: I now notice it mentions Spanish trains, although the link 404s

The one that is labeled as “German” is similar to, but noticeably different from, the hardware display actually in use on Berlin underground trains. The real one has proper descenders, and also has narrow i/t/l and wider m/w (that is, it's not monospace). Alas, the provided link 404s as well.