Custom property fallback

The backup value in var(), used when the property isn't set.

What is a custom property fallback?

A fallback is the second value in var(), used when the custom property isn't set.

.alert { color: var(--alert-color, crimson); }   /* crimson unless --alert-color is set */

Level: Freelancer · More CSS terms at this level

Updated September 27, 2026