1. CSS background-attachment

    Method of defining how a background image is attached to a scrollable element. Values include `scroll` (default), `fixed` and `local`.

  2. Background-clip: text

    Clipping a background image to the foreground text.

  3. CSS3 Background-image options

    New properties to affect background images, including background-clip, background-origin and background-size

  4. background-position-x & background-position-y

    CSS longhand properties to define x or y positions separately.

  5. CSS background-repeat round and space

    Allows CSS background images to be repeated without clipping.

  6. Background Sync API

    Provides one-off and periodic synchronization for Service Workers with an onsync event.

  7. CSS3 Border-radius (rounded corners)

    Method of making the border corners round. Covers support for the shorthand `border-radius` as well as the long-hand properties (e.g. `border-top-left-radius`)

  8. 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.

  9. CSS background-blend-mode

    Allows blending between CSS background images, gradients, and colors.

  10. ui-serif, ui-sans-serif, ui-monospace and ui-rounded values for font-family

    Allows more control when choosing system interface fonts

  11. CSS Flexible Box Layout Module

    Method of positioning elements in horizontal or vertical stacks. Support includes all properties prefixed with `flex`, as well as `display: flex`, `display: inline-flex`, `align-content`, `align-items`, `align-self`, `justify-content` and `order`.

  12. CSS3 Multiple backgrounds

    Method of using multiple images as a background

  13. SVG in CSS backgrounds

    Method of using SVG images as CSS backgrounds

  14. canvasrenderingcontext2d api: roundrect

  15. mlgraphbuilder api: roundeven

  16. offscreencanvasrenderingcontext2d api: roundrect

  17. path2d api: roundrect

  18. css property: border-image-repeat: round

  19. css property: border-image: round

  20. css property: corner-block-end-shape: round

  21. css property: corner-block-start-shape: round

  22. css property: corner-bottom-left-shape: round

  23. css property: corner-bottom-right-shape: round

  24. css property: corner-bottom-shape: round

  25. css property: corner-end-end-shape: round

  26. css property: corner-end-start-shape: round

  27. css property: corner-inline-end-shape: round

  28. css property: corner-inline-start-shape: round

  29. css property: corner-left-shape: round

  30. css property: corner-right-shape: round

  31. css property: corner-shape: round

  32. css property: corner-start-end-shape: round

  33. css property: corner-start-start-shape: round

  34. css property: corner-top-left-shape: round

  35. css property: corner-top-right-shape: round

  36. css property: corner-top-shape: round

  37. css property: stroke-linecap: round

  38. css property: stroke-linejoin: round

  39. types: `<basic-shape>`: `polygon()`: round

  40. types: `<corner-shape-value>`: round

  41. types: `round()`

  42. types: `round()`: mix `<percentage>` with `<length>` and `<number>` parameters

  43. javascript built-in: math: round

  44. javascript built-in: temporal api: duration: round

  45. javascript built-in: temporal api: instant: round

  46. javascript built-in: temporal api: plaindatetime: round

  47. javascript built-in: temporal api: plaintime: round

  48. javascript built-in: temporal api: zoneddatetime: round