Support for none true color terminals

[tasmo]

I am trying to use this colorscheme and some highlight groups are identical to the background - not sure why. my TERM is xterm-256color. Tried it in sakura, konsole, and wezterm; with and without tmux - same results.

I have used vim -u NONE to start. then set nocompatible, and syntax on. Then set colorscheme to humanoid. Still seeing the same issue.

Tried changing the background to dark/light. keywords are still the same color as background.

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Album: https://imgur.com/a/QqkTgsX

I included screenshots with default and corvine (my preferred theme before humanoid).

The vim session in the screenshots are with my vimrc loaded. However, the result is the same starting with vim -u NONE, then running the following:

syntax on
set nu
colorscheme humanoid