Case-insensitive CSS attribute selectors

Including an `i` before the `]` in a CSS attribute selector causes the attribute value to be matched in an ASCII-case-insensitive manner. For example, `[b="xyz" i]` would match both `<a b="xyz">` and `<a b="XYZ">`.

:is() CSS pseudo-class

The `:is()` (formerly `:matches()`, formerly `:any()`) pseudo-class checks whether the element at its position in the outer selector matches any of the selectors in its selector list. It's useful syntactic sugar that allows you to avoid writing out all the combinations manually as separate selectors. The effect is similar to nesting in Sass and most other CSS preprocessors.

CSS :read-only and :read-write selectors

:read-only and :read-write pseudo-classes to match elements which are considered user-alterable

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)

CSS3 selectors

Advanced element selection using selectors including: `[foo^="bar"]`, `[foo$="bar"]`, `[foo*="bar"]`, `:root`, `:nth-child()`, `:nth-last-child()`, `:nth-of-type()`, `:nth-last-of-type()`, `:last-child`, `:first-of-type`, `:last-of-type`, `:only-child`, `:only-of-type`, `:empty`, `:target`, `:enabled`, `:disabled`, `:checked`, `:not()`, `~` (general sibling)

css at-rule: `@keyframes`: named timeline range keyframe selectors

css selector: `::-moz-page`

css selector: `:active`

css selector: `:autofill`

css selector: `::backdrop`

css selector: `:blank`

css selector: `:buffering`

css selector: `:checked`

css selector: closed

css selector: `::cue`

css selector: `:defined`

css selector: `:disabled`

css selector: `:empty`

css selector: `:enabled`

css selector: `:focus`

css selector: `:fullscreen`

css selector: `:future`

css selector: `:host`

css selector: `:host()`

css selector: `:hover`

css selector: `:in-range`

css selector: `:invalid`

css selector: `:lang()`

css selector: `:last-child`

css selector: `:link`

css selector: `:modal`

css selector: `:muted`

css selector: `:only-child`

css selector: open

css selector: `::part`

css selector: `:past`

css selector: `:paused`

css selector: `:playing`

css selector: `:read-write`

css selector: `:required`

css selector: `:root`

css selector: `:scope`

css selector: `:seeking`

css selector: `::slotted`

css selector: `:stalled`

css selector: `:target`

css selector: `:user-valid`

css selector: `:valid`

css selector: `:visited`

css selector: `:where()`