IMO if your terminal theme does not provide high contrast for "white" text on the default or "black" backgrounds, that's for you to fix. If you want a light terminal then change the color scheme to map "black" to a bright color and "white" to a dark color while making sure that other colors have good contrast to your "black". Don't just change the default foreground and background color and expect every single color using program to fix your mess.
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IMO if your terminal theme does not provide high contrast for "white" text on the default or "black" backgrounds, that's for you to fix. If you want a light terminal then change the color scheme to map "black" to a bright color and "white" to a dark color while making sure that other colors have good contrast to your "black". Don't just change the default foreground and background color and expect every single color using program to fix your mess.