Dark mode colors without duplicating values
You defined every variable in :root and again inside @media (prefers-color-scheme: dark). light-dark() holds both values in one place so you do not repeat yourself.
2 color-scheme: light dark;
3 color: light-dark(#111, #eee);
4}
5/* One place per property */
2 --text: #111;
3 --bg: #fff;
4}
5
6@media (prefers-color-scheme: dark) {
7:root {
8 --text: #eee;
9 --bg: #222;
10}
11}
12/* Every variable declared twice */
Browser Support for light-dark()
Since 2024 this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.
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No duplication
First argument is light, second is dark. One declaration, no @media block for each variable.
Works with variables
light-dark(var(--text-light), var(--text-dark)) fits right into a design token setup.
Any property
Use it for color, background, border-color, fill, stroke. Anything that takes a color.
How it works
The old approach was to set your colors (or CSS variables) in :root, then open a @media (prefers-color-scheme: dark) block and redeclare every variable or property for dark mode. That meant every color in two places and easy drift between light and dark.
The modern approach is light-dark(lightValue, darkValue). The browser picks the first value in light mode and the second in dark mode, based on prefers-color-scheme. Pair it with color-scheme: light dark so form controls and scrollbars follow. You can use raw colors or variables: light-dark(var(--text), var(--text-dark)).