UPDATE 8/1/25: Added a script to quickly change tmux themes based on gsettings's preferred colour scheme, and a few words on VSCode's terminal profile system.

A new year's resolution of mine was to use light colour palettes more often. Dark colour schemes are OK in low-light, but unfortunately have several problems in non-low-light situations.

1. Light text on dark backgrounds provide worse contrast, making it harder to read, and increasing eye strain.

2. The human brain is adapted to finding dark objects in light conditions rather than vice-versa.

3. Excessive dark mode during the day under bright light strains your eyes.

Most operating systems now offer a means to switch colour palettes. My Google Pixel does this automatically. I use Gnome, which has a handy toggle for "Dark style", and this tells applications using GTK to follow a particualar theme.

Browsers

Firefox and Chrome can automatically set their preferences for light and dark mode based on the settings of the operating system. Unfortunately, this stops you using custom theming. If you're on Gnome, set both to use the GTK theme.

Web pages

I've ranted about this before, but your browser can tell your page that it prefers to use a colour scheme that is either dark or light. It can do this in CSS, using the prefers-color-scheme property.

:where(body) {
    --background-color: #FFF;
    --text-color: #222;
}
@media (prefers-color-scheme: dark) {
    :where(body) {
        --background-color: hsl(228, 5%, 15%);
        --text-color: hsl(228, 5%, 80%);
    }
}

body {
    background-color: var(--background-color);
    color: var(--text-color);
}

There's no need to have any JavaScript rewriting of the DOM or anything like that. There's no need to use a Greasemonkey script either. Just use this property. Trust the browser for theming because the browser trusts the operating system for theming. Don't roll your own theming. Just use prefers-color-scheme. Talking about you, 𝕏.

Terminals

Ghostty

I use Ghostty, which does support light and dark mode.

theme = dark:Tomorrow Night,light:Tomorrow

gnome-terminal

On machines where I can't use Ghostty and have to use gnome-terminal instead, I keep a dark mode profile available for use. It doesn't support automatic colour palette switching, unfortunately.

tmux

As far as I know, tmux does not offer this functionality, which is a shame. Colours can handled by the terminal, but status bar colours can't be.

I keep a tomorrow-night.conf file and a tomorrow.conf file in tmux's XDG directory, and just source-file ~/.config/tmux/<tomorrow|tomorrow-night>.conf to change themes.

I wrote a quick script called curtains that simply changes this source-file based on the current Gnome preferred colour scheme.

#!/usr/bin/env sh

function darken_tmux(){
	echo "Closing curtains..."
	sed -i -e 's/tomorrow.conf/tomorrow-night.conf/g' ~/.config/tmux/tmux.conf
	echo "Please reload your tmux config."
}

function lighten_tmux(){
	echo "Opening curtains..."
	sed -i -e 's/tomorrow-night.conf/tomorrow.conf/g' ~/.config/tmux/tmux.conf
	echo "Please reload your tmux config."
}

function curtains(){
	COLORSCHEME="$(gsettings get org.gnome.desktop.interface color-scheme)"
	if [ $COLORSCHEME = "'prefer-dark'" ]; then
		darken_tmux
	else
		lighten_tmux
	fi
}

curtains $1

Text editors

vim

I use vim, which ships with a colour scheme that emulates the gruvbox colour scheme. It's called retrobox, it looks decent, plays well with treesitter in nvim, and crucially supports background.

set background=light for a light background, set background=dark for a dark background, and it follows the settings of your terminal emulator and system.

VSCode

There are built-in dark and light modes, but if you want to use them, you have to enable the Auto Detect Color Scheme option in the preferences. This does follow what your operating system prefers.

I use the Tomorrow and Tomorrow-Night colour schemes and set those though the Workbench: Preferred Light Color Theme and Workbench: Preferred Dark Color Theme options respectively.

As for the terminal, it depends what terminal you're using. If you're using gnome-terminal, you can change the profile through Terminal Profiles.