1. Case-insensitive CSS attribute selectors

    Including an `i` before the `]` in a CSS attribute selector causes the attribute value to be matched in an ASCII-case-insensitive manner. For example, `[b="xyz" i]` would match both `<a b="xyz">` and `<a b="XYZ">`.

  2. :is() CSS pseudo-class

    The `:is()` (formerly `:matches()`, formerly `:any()`) pseudo-class checks whether the element at its position in the outer selector matches any of the selectors in its selector list. It's useful syntactic sugar that allows you to avoid writing out all the combinations manually as separate selectors. The effect is similar to nesting in Sass and most other CSS preprocessors.

  3. CSS :read-only and :read-write selectors

    :read-only and :read-write pseudo-classes to match elements which are considered user-alterable

  4. CSS 2.1 selectors

    Basic CSS selectors including: `*` (universal selector), `>` (child selector), `:first-child`, `:link`, `:visited`, `:active`, `:hover`, `:focus`, `:lang()`, `+` (adjacent sibling selector), `[attr]`, `[attr="val"]`, `[attr~="val"]`, `[attr|="bar"]`, `.foo` (class selector), `#foo` (id selector)

  5. CSS3 selectors

    Advanced element selection using selectors including: `[foo^="bar"]`, `[foo$="bar"]`, `[foo*="bar"]`, `:root`, `:nth-child()`, `:nth-last-child()`, `:nth-of-type()`, `:nth-last-of-type()`, `:last-child`, `:first-of-type`, `:last-of-type`, `:only-child`, `:only-of-type`, `:empty`, `:target`, `:enabled`, `:disabled`, `:checked`, `:not()`, `~` (general sibling)

  6. css selector: `:-moz-broken`

  7. css selector: `::-moz-page`

  8. css selector: `:-moz-ui-valid`

  9. css selector: ::-webkit-resizer

  10. css selector: `:active`

  11. css selector: `::backdrop`

  12. css selector: `:blank`

  13. css selector: `:checked`

  14. css selector: `::cue`

  15. css selector: `:defined`

  16. css selector: `:disabled`

  17. css selector: `:empty`

  18. css selector: `:enabled`

  19. css selector: `:first-child`

  20. css selector: `:first-of-type`

  21. css selector: `:focus`

  22. css selector: `:focus-visible`

  23. css selector: `:fullscreen`

  24. css selector: `:host`

  25. css selector: `:host()`

  26. css selector: `:hover`

  27. css selector: `:in-range`

  28. css selector: `:invalid`

  29. css selector: `:is()`

  30. css selector: `:lang()`

  31. css selector: `:last-child`

  32. css selector: `:last-of-type`

  33. css selector: `:link`

  34. css selector: `:nth-child()`

  35. css selector: `:nth-of-type()`

  36. css selector: `:only-child`

  37. css selector: `:only-of-type`

  38. css selector: `::part`

  39. css selector: `::placeholder`

  40. css selector: `:read-write`

  41. css selector: `:required`

  42. css selector: `:root`

  43. css selector: `:scope`

  44. css selector: `::slotted`

  45. css selector: `:target`

  46. css selector: `:target-within`

  47. css selector: `:user-invalid`

  48. css selector: `:valid`

  49. css selector: `:visited`

  50. css selector: `:where()`