[MathMonkeyMan]

font-family: Verdana, Geneva, sans-serif;

My computer has neither Verdana nor Geneva, and my browser's default sans-serif is Noto Sans, which has bars on the upper case "I".

Verdana does, too. It looks like Geneva does not (<http://www.identifont.com/show?1O3>), so you're probably using Geneva.

Maybe Verdana is the default for Windows, Geneva for MacOS, and "other" for Linuxes.

[xamuel]

One place where the big i and small L look almost identical, and a pretty funny/annoying place for them to do so, is when you're typing a WiFi password in OSX (if you toggle "Show password"), at least as of MacOS Monterey 12.1. I also see them as almost identical in my browser's URL bar (Firefox 148.0.2 on aforesaid version of OSX) which isn't just an annoyance but might even be a security concern!