1. 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.

  2. hidden attribute

    The `hidden` attribute may be applied to any element, and effectively hides elements similar to `display: none` in CSS.

  3. Large, Small, and Dynamic viewport units

    Viewport units similar to `vw` and `vh` that are based on shown or hidden browser UI states to address shortcomings of the original units. Currently defined as the `lvh`, `lvw`, `svh`, `svw`, `dvh`, `dvw` units.

  4. WAI-ARIA Accessibility features

    Method of providing ways for people with disabilities to use dynamic web content and web applications.

  5. document api: hidden

  6. elementinternals api: ariahidden

  7. element api: ariahidden

  8. htmlelement api: hidden

  9. html element: input: `type="hidden"`

  10. html attribute: hidden

  11. html attribute: hidden: `until-found` value