1. Media Queries: interaction media features

    Allows a media query to be set based on the presence and accuracy of the user's pointing device, and whether they have the ability to hover over elements on the page. This includes the `pointer`, `any-pointer`, `hover`, and `any-hover` media features.

  2. CSS 2.1 selectors

    Basic CSS selectors including: `*` (universal selector), `>` (child selector), `:first-child`, `:link`, `:visited`, `:active`, `:hover`, `:focus`, `:lang()`, `+` (adjacent sibling selector), `[attr]`, `[attr="val"]`, `[attr~="val"]`, `[attr|="bar"]`, `.foo` (class selector), `#foo` (id selector)

  3. CSS pointer-events (for HTML)

    This CSS property, when set to "none" allows elements to not receive hover/click events, instead the event will occur on anything behind it.

  4. css at-rule: `@media`: `any-hover` media feature

  5. css at-rule: `@media`: `hover` media feature

  6. css selector: `:hover`

  7. css selector: `:hover`: all elements support

  8. css selector: `:hover`: `<a>` element support

  9. css selector: `:hover`: pseudo-element support