@custom-media working behind a flag in Firefox Nightly! @custom-media --motionOK (prefers-reduced-motion: no-preference); @media (--motionOK) { transition: transform .3s ease; } Lovely syntax. Open Props has ~45 ready to go , peep the spec , or visit MDN for more info.

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Adam Argyle

The @custom-media CSS feature is now available behind a flag in Firefox Nightly, allowing developers to define reusable media query aliases. The syntax enables creating named media queries like --motionOK for prefers-reduced-motion checks, making CSS more maintainable. Open Props library already includes around 45 ready-to-use custom media queries.

Custom Media · January 23, 2026