Astro Guideline: Styling — Use scoped styles by default. Description: Astro scopes styles to component automatically. Do: <style> for component-specific styles. Don't: Global styles for everything. Good Example: <style> h1 { } </style> (scoped). Bad Example: <style is:global> for everything. Severity: Medium. Docs: https://docs.astro.build/en/guides/styling/#scoped-styles.