Regrowth

🔬 Regrowth is a monstrous laboratory experiment in container queries brought to life.

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• Parses all link elements and extracts all relevant @media rules.
• Listens for dynamically added stylesheets using MutationObserver.
• Parses the related CSS rules using the browser's internal CSS AST.
• Inserts iframe elements relative to each matching selector.
• Attaches resize events on the aformentioned iframe elements.
• Updates stylesheets accordingly using matchMedia on resize.

Getting Started

You use the familiar @media rules in your CSS stylesheet – the only difference is that to make a rule a container query rule, you need to append container as a media rule.

@media container, screen and (max-width: 256px) {
    my-element {
        background-color: orange;
    }
}

Removing the container rule will make the @media rule a normal CSS media rule relative to the window's dimensions, as opposed to the element's dimensions. Although we could allow the container to be specified anywhere with ease, it's required to be the first rule to make it obvious that the @media rule is not a regular media query.

In the above example the my-element rule will apply to all nested selectors when screen and (max-width: 256px) is applicable to the element.