Use Cases and Requirements for Element Queries

Editor’s Draft,

This version:
Issue Tracking:
Tommy Hodgins (WICG)
Former Editors:
Mat Marquis (RICG)
Scott Jehl (Filament Group)
Version History:
Commit History
IRC: #wicg on W3C’s IRC


This document captures the use cases and requirements for standardizing a solution for element queries. The use cases and requirements are currently being gathered with consultation with WICG group members, and the general public.

Status of this document

This is an unofficial draft. It is provided for discussion only and may change at any moment. Its publication here does not imply endorsement of its contents by W3C. Don’t cite this document other than as work in progress.

1. Introduction

Given a complex responsive layout, developers often require granular control over how the contents of an individual module will respond relative to the size of their parent container rather than the viewport size. This limitation conflicts with the goal of creating modular, independent components, often requiring a number of redundant CSS, complex exception cases, and workarounds, and the problem compounds itself depending on how dramatically a module adapts at each of its breakpoints.

For the purposes of this document, an element query refers not to a specific syntax or proposed method of addressing the use cases that follow, but a method of controlling styling based on the size of a containing element.

This document presents some of the use cases that “element queries” would solve, in allowing authors to define styles (chiefly, layouts) within an individual module on the basis of the size of the module itself rather than the viewport. The goal is to demonstrate, beyond a reasonable doubt, the need for a standardized method of allowing content to respond to its container’s dimensions (as opposed to the overall viewport size). This would facilitate the construction of layouts comprised of many modular, independent HTML components with a minimum of duplicated CSS and overrides specific to the modules’ parent containers.

In formulating the requirements, this document tries to be neutral—it is not predicated on any solution. The document only tries to describe the use cases and what the WICG understands, from practice, would be needed to address the use cases in the form of requirements. The WICG expect that a technical specification can be created to formally address each or all of the requirements (i.e., the solution).

2. Use Cases

This document reflects the efforts of members from the Responsive Issues Community Group (RICG) and Web Platform Incubator Community Group (WICG), and with ongoing feedback from the designer/developer community via blog posts, informal polls, and other social media sources. The WICG’s goal for this document is to make sure that developer requirements for element queries have been captured for the purpose of standardization.

The following use cases represent common usage scenarios:

Figure 1 is an example of a relatively simple and fully self-contained module’s layout, using only a single min-width media query to reflow content.

An example of a self-contained module that requires a single breakpoint.

In this layout, this module can occupy containing elements of varying widths, governed by multiple breakpoints. In small viewports, we’ll be using a linear layout where each of our five modules occupy the full viewport — this layout is covered by the base styles outside of our media query. At higher breakpoints, these modules will be displayed side-by-side: three across, then below that two across. The three-across layout will be covered by the global styles within our viewport-based media query. Parent-specific overrides will need to be written for the two-across layout, as these modules will need to shift to their wide-format at a smaller viewport size than the ones above them.

Some of the contexts in which the module in fig. 1 might appear.

In order to accomplish this layout, a developer would need to duplicate all of this module’s “wide layout” styles into a second viewport-based media query—set to apply at a smaller min-width than the global breakpoint styles—with all of our styles scoped to a parent container. This now means that any future edits or bug fixes to the wide-format layout styles will need to be made in multiple places, and this maintenance cost increases exponentially with each module-level breakpoint required.

A stylesheet heatmap showing the redundant styles required to accomodate the layout variations in fig. 2

Similarly, introducing a new context unlike the previous two—shown in figure 4 with the introduction of a “sidebar” on an interior page layout—means duplicating or overriding all of a module’s media queries yet again.

A wireframe introducing a new context for the modules in fig. 1, where no breakpoint should apply

The module in this new sidebar context will never need to reflow to the wider layout, and as such we’re left with two options: scoping all of our modules—with the exception of the two-across layout—to a parent class, or introducing a new media query that overrides all of our wide-layout styles based on the sidebar’s parent class. Despite the relative simplicity of our module and our overall page layouts, one is left with a bloated and difficult to maintain stylesheet.

A stylesheet heatmap showing added redundancy and rewriting of existing styles required to accommodate the layout variation in fig. 4

3. Requirements

The use cases give rise to the following requirements:

4. Open issues

We are tracking open issues on Github. Please help us close them!

5. Change history

A complete history of changes is available on Github.

You can also see all closed issues relating to this document.

6. Acknowledgements

A complete list of participants of the Web Platform Incubator Community Group is available at the W3C Community Group Website.


Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology. The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification.

All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [RFC2119]

Examples in this specification are introduced with the words “for example” or are set apart from the normative text with class="example", like this:

This is an example of an informative example.

Informative notes begin with the word “Note” and are set apart from the normative text with class="note", like this:

Note, this is an informative note.


Terms defined by this specification


Normative References

S. Bradner. Key words for use in RFCs to Indicate Requirement Levels. March 1997. Best Current Practice. URL: