Multiple elements to have the appearance of a card -- how to implement?

[dz4k]

I wanted to have <details> styling be derived from missing-card. This is not possible in any standardized CSS without adding , details to card.css, or duplicating styles.

In CSS preprocessors, we have things like extends, but I'd prefer if we stuck to a CSS dialect that will probably be standard in the future.

[dz4k]

https://github.com/travco/postcss-extend

This plugin adds Sass-style @extend, which seems like what we want.

I couldn't find any action towards a native CSS version of this. There was the @apply proposal, but that died out (I didn't like it anyway, but there doesn't seem to be any alternative).

I just want a way to say "pretend that elements which match this selector also match this other selector"