Custom properties

Custom properties are CSS properties prefixed with -- that set values you can reuse with the var() function. For example, you can set a --key-color property to reuse as border-color: var(--key-color). Also known as CSS variables.

Baseline Status: Achieved Widely Available on Oct 5, 2019 (Cross-browser Newly Available since Apr 5, 2017).

Desktop Browser Engine Support

Google Chrome

49

Supported

Mozilla Firefox

31

Supported

Apple Safari

9.1

Supported

Microsoft Edge

15

Supported

Mobile Browser Engine Support

Chrome Android

49

Firefox Android

31

Safari iOS

9.3

Specifications and References

Specification ↗ Can I Use (css-variables) ↗ Feature XML ↗

MDN Browser Compat Data Keys:

css.properties.custom-property ↗ css.types.var ↗