custom-property
Commonly known as 'CSS Variables'. They allow you to store values (like colors or sizes) in a name starting with '--' and reuse them throughout your stylesheet using the 'var()' function.
Quick example
:root {
--brand-color: #3b82f6;
}
.button {
background-color: var(--brand-color);
}custom-property Browser Support
Widely available Since 2017 96% global usage
This feature is well established and works across many devices and browser versions. It has been available across browsers since 2017.
Safe to use without fallbacks.
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9.1+
15+