added release notes for @container style() queries (#43473)

* added release notes for @container style() queries

* Update files/en-us/mozilla/firefox/experimental_features/index.md

Co-authored-by: Dipika Bhattacharya <dipika@foss-community.org>

* Update files/en-us/mozilla/firefox/releases/149/index.md

Co-authored-by: Dipika Bhattacharya <dipika@foss-community.org>

* maded changes to reflect experimental page

---------

Co-authored-by: Dipika Bhattacharya <dipika@foss-community.org>

Author: dletorey

files/en-us/mozilla/firefox/experimental_features/index.md

@@ -375,6 +375,20 @@ The media-based pseudo-classes {{cssxref(":buffering")}}, {{cssxref(":muted")}},
 - `dom.media.pseudo-classes.enabled`
   - : Set to `true` to enable.
 
+### `@container style()` queries
+
+The [`@container`](/en-US/docs/Web/CSS/Reference/At-rules/@container) CSS at-rule supports [`style()`](/en-US/docs/Web/CSS/Guides/Containment/Container_size_and_style_queries#container_style_queries) queries. This allows you to check if a container has a valid CSS declaration, a CSS property, or a custom property, and apply styles to its children accordingly. ([Firefox bug 2014404](https://bugzil.la/2014404)).
+
+| Release channel   | Version added | Enabled by default? |
+| ----------------- | ------------- | ------------------- |
+| Nightly           | 149           | Yes                 |
+| Developer Edition | 149           | No                  |
+| Beta              | 149           | No                  |
+| Release           | 149           | No                  |
+
+- `layout.css.style-queries.enabled`
+  - : Set to `true` to enable.
+
 ## SVG
 
 **No experimental features in this release cycle.**

files/en-us/mozilla/firefox/releases/149/index.md

@@ -143,3 +143,7 @@ You can find more such features on the [Experimental features](/en-US/docs/Mozil
 - **`alpha` & `colorspace` attributes in `color` input elements** (Nightly only): `dom.forms.html_color_picker.enabled`
 
   The HTML [`<input type="color">`](/en-US/docs/Web/HTML/Reference/Elements/input/color) element supports [`alpha`](/en-US/docs/Web/HTML/Reference/Elements/input/color#alpha) & [`colorspace`](/en-US/docs/Web/HTML/Reference/Elements/input/color#colorspace) attributes. ([Firefox bug 1919718](https://bugzil.la/1919718)).
+
+- **`@container style()` queries** (Nightly): `layout.css.style-queries.enabled`
+
+  The [`@container`](/en-US/docs/Web/CSS/Reference/At-rules/@container) CSS at-rule supports [`style()`](/en-US/docs/Web/CSS/Guides/Containment/Container_size_and_style_queries#container_style_queries) queries. This allows you to check if a container has a valid CSS declaration, a CSS property, or a custom property, and apply styles to its children accordingly. ([Firefox bug 2014404](https://bugzil.la/2014404)).