1. CSS background-repeat round and space

    Allows CSS background images to be repeated without clipping.

  2. CSS Counter Styles

    The @counter-style CSS at-rule allows custom counter styles to be defined. A @counter-style rule defines how to convert a counter value into a string representation.

  3. CSS Counters

    Method of controlling number values in generated content, using the `counter-reset` and `counter-increment` properties.

  4. CSS3 image-orientation

    CSS property used generally to fix the intended orientation of an image. This can be done using 90 degree increments or based on the image's EXIF data using the "from-image" value.

  5. CSS ::marker pseudo-element

    The `::marker` pseudo-element allows list item markers to be styled or have their content value customized.

  6. CSS overflow property

    Originally a single property for controlling overflowing content in both horizontal & vertical directions, the `overflow` property is now a shorthand for `overflow-x` & `overflow-y`. The latest version of the specification also introduces the `clip` value that blocks programmatic scrolling.

  7. CSS overflow: overlay

    The `overlay` value of the `overflow` CSS property is a non-standard value to make scrollbars appear on top of content rather than take up space. This value is deprecated and related functionality being standardized as [the `scrollbar-gutter` property](mdn-css_properties_scrollbar-gutter).

  8. CSS revert value

    A CSS keyword value that resets a property's value to the default specified by the browser in its UA stylesheet, as if the webpage had not included any CSS. For example, `display:revert` on a `<div>` would result in `display:block`. This is in contrast to the `initial` value, which is simply defined on a per-property basis, and for `display` would be `inline`.

  9. CSS3 Cursors (original values)

    CSS3 cursor values added in the 2004 spec, including none, context-menu, cell, vertical-text, alias, copy, no-drop, not-allowed, nesw-resize, nwse-resize, col-resize, row-resize and all-scroll.

  10. CSS currentColor value

    A CSS value that will apply the existing `color` value to other properties like `background-color`, etc.

  11. Datalist element

    Method of setting a list of options for a user to select in a text field, while leaving the ability to enter a custom value.

  12. Web Storage - name/value pairs

    Method of storing data locally like cookies, but for larger amounts of data (sessionStorage and localStorage, used to fall under HTML5).

  13. relList (DOMTokenList)

    Method of easily manipulating rel attribute values on elements, using the DOMTokenList object (similar to classList).

  14. SVG vector-effect: non-scaling-stroke

    The `non-scaling-stroke` value for the `vector-effect` SVG attribute/CSS property makes strokes appear as the same width regardless of any transformations applied.

  15. audioparam api: linearramptovalueattime

  16. cssvaluelist api

  17. cssvaluelist api: item

  18. cssvaluelist api: length

  19. devicelightevent api: value

  20. domtokenlist api: replace: `return()`'s value is a boolean, not void as it used to be.

  21. domtokenlist api: value

  22. domtokenlist api: values

  23. headers api: lexicographical sorting, and values from duplicate header names combined when iterated.

  24. highlightregistry api: values

  25. highlight api: values

  26. htmlinputelement api: defaultvalue

  27. htmlinputelement api: value

  28. htmlinputelement api: valueasdate

  29. htmlinputelement api: valueasnumber

  30. htmllielement api: value

  31. nodelist api: values

  32. presentationavailability api: value

  33. radionodelist api: value

  34. validitystate api: valuemissing

  35. css at-rule: `@font-feature-values`: `@stylistic`

  36. css property: -moz-orient: `inline` and `block` values

  37. css property: appearance: `<compat-auto>` (compatibility values `searchfield`, `textarea`, `push-button`, `slider-horizontal`, `checkbox`, `radio`, `square-button`, `menulist`, `listbox`, `meter`, `progress-bar`, `button`)

  38. css property: background: values of `background-clip` longhand

  39. css property: clear: flow-relative values `inline-start` and `inline-end`

  40. css property: float: flow-relative values `inline-start` and `inline-end`

  41. css property: overflow-clip-box: two values; property as shorthand

  42. css property: overflow-x: `clip` value

  43. css property: overflow-y: `clip` value

  44. css property: overflow: `clip` value

  45. css property: resize: support for flow-relative values `block` and `inline`

  46. css property: text-align: prefixed `center`, `left`, and `right` values for block alignment

  47. css property: text-align: flow-relative values `start` and `end`

  48. css property: text-underline-offset: percentage values

  49. html element: li: value

  50. svg element: fecomposite: operator: `lighter` value