1. CSS background-repeat round and space

    Allows CSS background images to be repeated without clipping.

  2. CSS background-position edge offsets

    Allows CSS background images to be positioned relative to the specified edge using the 3 to 4 value syntax. For example: `background-position: right 5px bottom 5px;` for positioning 5px from the bottom-right corner.

  3. Media Queries: Range Syntax

    Syntax improvements to make media queries using features that have a "range" type (like width or height) less verbose. Can be used with ordinary mathematical comparison operators: `>`, `<`, `>=`, or `<=`. For example: `@media (100px <= width <= 1900px)` is the equivalent of `@media (min-width: 100px) and (max-width: 1900px)`

  4. CSS Relative color syntax

    Relative color syntax in CSS allows a color to be defined relative to another color using the `from` keyword and optionally `calc()` for any of the color values.

  5. CSS @when / @else conditional rules

    Syntax allowing CSS conditions (like media and support queries) to be written more simply, as well as making it possible to write mutually exclusive rules using `@else` statements.

  6. csspropertyrule api: syntax

  7. css at-rule: `@container`: style queries for custom properties: range syntax

  8. css at-rule: `@media`: `or` syntax from media queries level 4

  9. css at-rule: `@property`: `syntax` descriptor

  10. css property: background-repeat: two-value syntax (different values for x & y directions)

  11. css property: cursor: `url()` positioning syntax

  12. css property: font-size-adjust: two-value syntax

  13. css property: font-stretch: `<percentage>` syntax

  14. css property: font-weight: `<number>` syntax

  15. css property: overflow: multiple keyword syntax for `overflow-x` and `overflow-y`

  16. css property: text-overflow: two-value syntax

  17. css property: transform-origin: three-value syntax

  18. css selector: `:nth-last-child()`: `of <selector>` syntax

  19. types: `attr()`: `type(<syntax>)` function

  20. types: `attr()`: `type(<syntax>)` function: `<angle>`

  21. types: `attr()`: `type(<syntax>)` function: `<color>`

  22. types: `attr()`: `type(<syntax>)` function: `<custom-ident>`

  23. types: `attr()`: `type(<syntax>)` function: `<ident>`

  24. types: `attr()`: `type(<syntax>)` function: `<image>`

  25. types: `attr()`: `type(<syntax>)` function: `<integer>`

  26. types: `attr()`: `type(<syntax>)` function: `<length>`

  27. types: `attr()`: `type(<syntax>)` function: `<number>`

  28. types: `attr()`: `type(<syntax>)` function: `<percentage>`

  29. types: `attr()`: `type(<syntax>)` function: `<resolution>`

  30. types: `attr()`: `type(<syntax>)` function: `<string>`

  31. types: `attr()`: `type(<syntax>)` function: `<time>`

  32. types: `attr()`: `type(<syntax>)` function: `<url>`

  33. types: `<color>`: `color()` (profiled color values): relative `color()` syntax

  34. types: `<gradient>`: `radial-gradient()`: `at` syntax

  35. types: `<gradient>`: `repeating-radial-gradient()`: `at` syntax

  36. types: `if()`: `style()` queries: range syntax for style queries

  37. types: `<position>`: four-value syntax for offset from any edge

  38. types: `<position>`: syntax combining a keyword and `<length>` or `<percentage>`

  39. javascript built-in: syntaxerror

  40. javascript built-in: syntaxerror: `syntaxerror` is serializable

  41. javascript built-in: syntaxerror: `syntaxerror()` constructor

  42. grammar: hashbang (`#!`) comment syntax

  43. javascript operator: spread syntax (...)

  44. javascript operator: spread syntax (...): spread in array literals

  45. javascript operator: spread syntax (...): spread in function calls

  46. javascript operator: spread syntax (...): spread in object literals

  47. javascript statement: import: import attributes (`with` syntax)

  48. empty tag syntax: <>