What is Astro's Starlight documentation theme?

Starlight is Astro's official documentation site template, built as an Astro integration. It provides everything needed for great documentation out of the box: Navigation sidebar: auto-generated from content collection structure. Full-text search: Pagefind-powered static search with zero JS on initial load. Internationalization: multi-language docs with locales config. Dark mode: automatic and manual toggle. Table of contents: per-page heading navigation. Versioning: support for multiple doc versions. Responsive design: works on mobile. Accessibility: WCAG compliant. Setup: npx create-astro --template starlight. Content: write docs as Markdown or MDX in src/content/docs/. Customize theme with CSS variables. Extend with Astro components. Starlight is used for many popular open-source projects' documentation. It achieves 100/100 Lighthouse scores for performance, accessibility, best practices, and SEO — making it ideal for developer documentation.