The stretch keyword, applicable to width and height (including min-width, max-width, min-height, and max-height), was introduced in Chromium browsers in June 2025. This value merges the non-standard -webkit-fill-available and -moz-available values, with the latter being available in Firefox since 2008.
Previously, without the @supports at-rule, implementing the correct value for each browser was challenging. It seems this was forgotten until Dave Rupert mentioned it on Bluesky a month ago:
Layout expert Miriam Suzanne recorded an explainer soon after. It’s worth examining this value further.
