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. backgroundfetchevent api

  15. backgroundfetchevent api: registration

  16. backgroundfetchmanager api

  17. backgroundfetchmanager api: fetch

  18. backgroundfetchmanager api: get

  19. backgroundfetchmanager api: getids

  20. backgroundfetchrecord api

  21. backgroundfetchrecord api: request

  22. backgroundfetchrecord api: responseready

  23. backgroundfetchregistration api

  24. backgroundfetchregistration api: abort

  25. backgroundfetchregistration api: downloaded

  26. backgroundfetchregistration api: failurereason

  27. backgroundfetchregistration api: id

  28. backgroundfetchregistration api: match

  29. backgroundfetchregistration api: matchall

  30. backgroundfetchregistration api: result

  31. backgroundfetchregistration api: uploaded

  32. backgroundfetchregistration api: uploadtotal

  33. backgroundfetchupdateuievent api

  34. backgroundfetchupdateuievent api: updateui

  35. canvasrenderingcontext2d api: roundrect

  36. offscreencanvasrenderingcontext2d api: roundrect

  37. path2d api: roundrect

  38. rtcstatsreport api: `remote-inbound-rtp` stats: `roundtriptime` in 'remote-inbound-rtp' stats

  39. rtcstatsreport api: `remote-inbound-rtp` stats: `roundtriptimemeasurements` in 'remote-inbound-rtp' stats

  40. rtcstatsreport api: `remote-outbound-rtp` stats: `roundtriptimemeasurements` in 'remote-outbound-rtp' stats

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

  42. css property: stroke-linecap: round

  43. css property: stroke-linejoin: round

  44. types: `round()`

  45. javascript built-in: math: round

  46. javascript built-in: temporal api: temporal.duration interface: temporal.duration.round()

  47. javascript built-in: temporal api: temporal.instant interface: temporal.instant.round()

  48. javascript built-in: temporal api: temporal.plaindatetime interface: temporal.plaindatetime.round()

  49. javascript built-in: temporal api: temporal.plaintime interface: temporal.plaintime.round()

  50. javascript built-in: temporal api: temporal.zoneddatetime interface: temporal.zoneddatetime.round()