Specificity is the algorithm used by browsers to determine the CSS declaration that is the most relevant to an element, which in turn, determines the property value to apply to the element. The specificity algorithm calculates the weight of a CSS selector to determine which rule from competing CSS declarations gets applied to an element.| developer.mozilla.org
The :where() CSS pseudo-class function takes a selector list as its argument, and selects any element that can be selected by one of the selectors in that list.| MDN Web Docs
A CSS pseudo-class is a keyword added to a selector that specifies a special state of the selected element(s). For example, the pseudo-class :hover can be used to select a button when a user's pointer hovers over the button and this selected button can then be styled.| MDN Web Docs
The :is() CSS pseudo-class function takes a selector list as its argument, and selects any element that can be selected by one of the selectors in that list. This is useful for writing large selectors in a more compact form.| MDN Web Docs
The CSS selector represents a particular pattern of element or elements in a tree structure. The term "selector" can refer to a simple selector, a compound selector, or a complex selector. When included in the :has() pseudo-class as a parameter, these selectors are referred to as relative selectors, representing elements relative to one or more anchor elements.| MDN Web Docs
The functional :has() CSS pseudo-class represents an element if any of the relative selectors that are passed as an argument match at least one element when anchored against this element. This pseudo-class presents a way of selecting a parent element or a previous sibling element with respect to a reference element by taking a relative selector list as an argument.| MDN Web Docs
Learn how the CSS `:not()` pseudo-class behaves when multiple selectors are passed as argument.| MDN Web Docs
Cascading Style Sheets (CSS) is a stylesheet language used to describe the presentation of a document written in HTML or XML (including XML dialects such as SVG, MathML or XHTML). CSS describes how elements should be rendered on screen, on paper, in speech, or on other media.| MDN Web Docs
1. Introduction| drafts.csswg.org
