Me(backend developer tries to be full stack): What type of font should I use for heading and body?

Client: Something like comic sans.

Me: should I use comic sans then?

Client: No this font is very informal though.

Me(thinking): All font seems similar to me.

After two hours of searching

Me: I think comic sans is best for you.

Client: No...

(Most difficult part of frontend is choosing appropriate font)

One thing I hate about receiving secured passwords on secured channels like Signal is the font. Really grinds my gears that I can't tell if that's an l (lowercase L) or an I (uppercase i) and more so with 0 and O. Uuuugghh