Glossary - WICG/cq-usecases GitHub Wiki

As the project moves long, we should collate any definitions of terms used to clarify where it helps

Element Query

An element query is a style rule that depends on properties of an element, like the element's own rendered dimensions as displayed in the browser.

Container Query

A container query is an element query that works within one or both of the following limitations:

• selector containment: when selectors inside the query are limited. E.g. Being written for the queried element and its descendants only

• style containment: when styles applied by a query are limited. E.g. To prevent their application from altering the validity of the query condition that applies them

Circularity

Circularity is present in CSS whenever the application of a property alters the validity of the rule that applied it. Circularity in CSS usually happens between 2 states (e.g. being hovered vs. not hovered), but with element queries comes the ability for authors to express circular styles without an upper bound on the number of intermediate states that can be reached.

Group Body Rule

The name referring to the CSS rules (i.e. the stylesheet) contained within a CSS at-rule like @media or @supports. The group body rule applies to the document while the at-rule is valid.