Here is a sample page showing some basic use cases for the proposed pseudo class :where(). Try resizing the browser window and the text area to see how the various elements respond. Note, no media queries were used to make this page, it all uses the javascript shim for the :where() pseudo class.

These buttons control the padding on the body, this demonstrates resizing that cannot be captured by media-queries.

On the left is a gallery that takes up 50% of the column, when the images get too small to be shown all at once it switches to showing them individually
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