1. CSS Environment Variables env()

    Usage of environment variables like `safe-area-inset-top`.

  2. CSS Variables (Custom Properties)

    Permits the declaration and usage of cascading variables in stylesheets.

  3. cssvariablereferencevalue api

  4. cssvariablereferencevalue api: `cssvariablereferencevalue()` constructor

  5. cssvariablereferencevalue api: fallback

  6. cssvariablereferencevalue api: variable

  7. css property: --*: `env()`: safe area inset variable `safe-area-inset-bottom`

  8. css property: --*: `env()`: safe area inset variable `safe-area-inset-left`

  9. css property: --*: `env()`: safe area inset variable `safe-area-inset-right`

  10. css property: --*: `env()`: safe area inset variable `safe-area-inset-top`

  11. css property: --*: `env()`: window controls overlay variable `titlebar-area-height`

  12. css property: --*: `env()`: window controls overlay variable `titlebar-area-width`

  13. css property: --*: `env()`: window controls overlay variable `titlebar-area-x`

  14. css property: --*: `env()`: window controls overlay variable `titlebar-area-y`

  15. css @apply rule