relnote(Fx145): -webkit-fill-available value supported (#41639)

Author: bsmth

files/en-us/mozilla/firefox/releases/145/index.md

@@ -36,6 +36,10 @@ Firefox 145 is the current [Beta version of Firefox](https://www.firefox.com/en-
 
 - The {{cssxref("text-autospace")}} property is now supported, allowing automatic spacing adjustments between characters from different scripts ([Firefox bug 1981086](https://bugzil.la/1981086), [Firefox bug 1869577](https://bugzil.la/1869577)).
 
+- Firefox now supports the legacy [`-webkit-fill-available` keyword](Web/CSS/WebKit_Extensions) as a value for the CSS {{cssxref("width")}} and {{cssxref("height")}} properties, to improve web compatibility.
+  This keyword is an alias for the recently-standardized `stretch` keyword (i.e., [`width: stretch`](/en-US/docs/Web/CSS/width#stretch) and [`height: stretch`](/en-US/docs/Web/CSS/height#stretch)) which isn't yet supported in Firefox.
+  ([Firefox bug 1988938](https://bugzil.la/1988938), [Firefox bug 1789477](https://bugzil.la/1789477)).
+
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