EQCSS

A CSS Reprocessor for Element Queries & More

CSS Element Queries Specification

Work has begun on a specification for container-style element queries syntax. This draft is still a work-in-progress and is not standard CSS.

What are Element Queries?

Element queries are a new way of thinking about responsive web design in CSS where the responsive conditions apply to individual elements on the page instead of the width or height of the browser.

Unlike CSS @media queries, @element queries can be based on more than just the width or height of the browser as well, you can change styles in a number of different situations, like how many lines of text or child elements an element contains.

Another concept that element queries brings to CSS is the idea of 'scoping' your styles to one element in the same way that JavaScript functions define a new scope for the variables they contain.

How to use EQCSS

EQCSS is a JavaScript plugin that lets you write element queries inside CSS today. With performance in mind, this plugin is written in pure JavaScript, so it doesn't require jQuery or any other libraries on your page in order to function - add EQCSS.js to your HTML and you're ready to get started!

Download EQCSS Zip

git clone https://github.com/eqcss/eqcss/archive/gh-pages.zip

Once you have downloaded a copy of EQCSS you will need to add it to every HTML page where you will be using element queries. It's best to add a <script> after your content, before the end of your <body> tag.

<script src=EQCSS.js></script>

If you need to support IE8 there is an optional polyfill available that adds @media queries and @element queries to IE8. Add this file to your HTML before where you added EQCSS:

<!--[if lt IE 9]><script src="EQCSS-polyfills.js"></script><![endif]-->

Alternatively, you can also grab EQCSS from npm with the following command:

npm install eqcss

Or from Yarn via

yarn add eqcss

CDN Hosted Links

EQCSS is also hosted on CDNjs and you can use the version hosted there for your projects: https://cdnjs.com/libraries/eqcss:

https://cdnjs.cloudflare.com/ajax/libs/eqcss/1.9.2/EQCSS-polyfills.min.js

https://cdnjs.cloudflare.com/ajax/libs/eqcss/1.9.2/EQCSS.min.js

Writing Element Queries

Now that you have EQCSS added to your HTML you're ready to write element queries. There are two ways you can add EQCSS to your site: the easiest way is by writing them inside your CSS either in a <style> or <link> in your HTML, or by isolating your EQCSS styles in a custom script type.

You can also link to EQCSS hosted in external files with either .css or .eqcss extensions.

Using the EQCSS script type

While not necessary, if you choose to isolate your EQCSS from your CSS you can store it in external .eqcss files and link them using a <script> tag like this:

<script type=text/eqcss src=styles.eqcss></script>

And you can include EQCSS scripts inline in your page like this as well:

<script type=text/eqcss>

  /* EQCSS goes here */

</script>

Running EQCSS

By default the plugin execute once when the content loads, and also whenever it detects browser resize (similar to @media queries). The EQCSS.apply() function can be called manually on other events too, like keyup or clicks, or even when specific elements are interacted with.

Note: Because EQCSS has the ability to execute JavaScript instructions stored inside EQCSS syntax, site owners using EQCSS should not allow unstruted user-supplied EQCSS syntax to be parsed and run with the EQCSS plugin. The risk is that users could execute malicious JavaScript instructions that could exfiltrate sensitive data from their session on your site to another server where it could be recorded. This is the same vulnerability as any 3rd party JavaScript plugin that can be used to execute JavaScript instructions.

Designing with Element Queries

Element Queries have the following syntax:

element_query = @element selector_list [ condition_list ] { css_code }

selector_list = " css_selector [ "," css_selector ]* "

condition_list = and ( query_condition : value ) [ "and (" query_condition ":" value ")" ]*

value = number [ css_unit ]

css_unit = % | px | pt | em | cm | mm | rem | ex | ch | pc | vw | vh | vmin | vmax

An EQCSS element query is a container query that begins with "@element", followed by one or more CSS selectors (comma-separated) in quotes (either single or double quotes), followed by one or more optional responsive conditions comprised of a query condition and a value separated by a colon, followed by one or more optional CSS rules wrapped in curly brackets.

For more info, view more about EQCSS syntax here: https://gist.github.com/tomhodgins/6237039fa07c2e4b7acd1c8b0f9549a9

Element Query Conditions

(Alternatively, for SCSS compatibility you can also use meta-selectors prefixed by eq_ instead of a : or $. These are eq_this or eq_self, eq_parent, eq_root, eq_prev, and eq_next)

CSS Functions

eval('') eval('') demo

CSS Units

ew element width ew demo
eh element height eh demo
emin element minimum emin demo
emax element maximum emax demo

Element Query Demos

And view many more EQCSS demos on Codepen: EQCSS pens on Codepen

Documentation & Tutorials

Try it Live

Here's a link to the EQCSS REPL where you can try writing EQCSS-enhance CSS live in your browser and share a custom link with others: http://elementqueries.com/repl.html

Browser Support

Lowest Version Supported:

IE 8+
Edge 13+
Safari 5.0+
Firefox 3.6+
Android 2.2+
iOS 4+
Windows Phone 8.1+

Lowest Version Tested:

Chrome 15+
Opera 10.6+

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