[NiLuJe]

The default config is setup for a dark color theme (e.g., Solarized Dark). Things may be "invisible" in some configurations; try switching the color theme from within htop itself (F2 > Colors).

Extremely exotic (and/or broken) terminal emulators may exacerbate the issue, too (e.g., broken/missing terminfo). (Or stuff that blatantly lies about/break the TERM env var).

Anything xterm compatible should behave, though, and I don't recall any issues in pactice with common terminal emulators on *nix (pretty much all the things that identify as xterm, which is effectively nearly everything these days), macOS (iTerm, Terminal) & Windows (PuTTY).