@astrojs/starlight@0.42.0

0.42.0

Sep 2, 2026

🍿 Minor Changes

#3572 292fb17 Thanks @HiDeoo! - Distributes package as JavaScript files with dedicated type declaration files instead of TypeScript source files.
#4121 2623ae6 Thanks @delucis! - Simplifies markup for Starlight’s mobile menu toggle

⚠️ Potentially breaking change: If you use a theme plugin, custom styles, or component overrides targeting the MobileMenuToggle button or PageFrame components, you may need to adjust these for the new markup. The button is no longer wrapped in a <starlight-menu-button> custom element and no longer uses the aria-expanded attribute. Instead, you can use the .sl-menu-button class name to target the button and the :popover-open pseudo-class to style the menu open state specifically.

In the following example, custom styles for the menu button are updated for the new approach:
```
 starlight-menu-button button {
 .sl-menu-button {
  color: var(--sl-color-text);
}

 starlight-menu-button[aria-expanded='true'] button {
 .sl-menu-button:has(~ :popover-open) {
  color: var(--sl-color-text-accent-high);
}
```
See MobileMenuToggle.astro and PageFrame.astro on GitHub for the full source code of the updated components.
#3572 292fb17 Thanks @HiDeoo! - Removes the tagline configuration option, which was never used.

If your configuration included a tagline option, you can safely remove it without any replacement.
#4134 6135f01 Thanks @HiDeoo! - Updates internal @astrojs/mdx, @astrojs/markdown-satteri, and satteri dependencies.

⚠️ BREAKING CHANGE: The following minimum versions are now required:
- astro v7.2.10 or later
- @astrojs/markdown-satteri 0.4.0 or later (if you use it)
- @astrojs/markdown-remark 7.3.0 or later (if you use it)
Please update Starlight and Astro together:
Terminal window
```
npx @astrojs/upgrade
```
#4121 2623ae6 Thanks @delucis! - Refactors Starlight’s mobile menu toggle to work when JavaScript fails or is disabled

⚠️ BREAKING CHANGE: This release drops official support for Chromium-based browsers prior to version 116 (released August 2023), Safari-based browsers prior to version 17.0 (released September 2023), and Firefox prior to version 125 (released April 2024). You can find a list of currently supported browsers and their versions using this browserslist query.

This change also removes the data-mobile-menu-expanded attribute, which was previously added to <body> while the mobile menu is open. If you have custom code that was depending on this attribute, you will need to update it to use a new selector to check if the mobile menu is open.

In the following example, a custom background colour for the site header while the menu is open is updated for the new approach:
```
 [data-mobile-menu-expanded] header {
 body:has(sl-sidebar-pane:popover-open) header {
  background-color: var(--sl-color-bg);
}
```