Re: [csswg-drafts] [css-shadow-parts-1] Can class name selectors apply to a part? (#3431)

> As much as I like declarative APIs, trying to define this in an attribute would be a mess.

Belated brain flash: What if we—hear me out, now—used CSS syntax? So states for the custom element could be defined with an `@state` rule in a stylesheet that applies to the shadow tree, similar to @tabatkins's [custom selectors proposal](

@state { /* state for the entire widget */
  checked: #checkbox:checked ;
  /* the widget is checked if the shadow element with id `checkbox` is checked */
@state drop-down-button { /* state for any element with part="drop-down-button" */
  focus: :focus-within;
  /* the part will match the focus pseudoclass for the outside tree
      if it contains a focused element within the shadow tree */

If allowing colons inside a value in a declaration-like structure is a syntax issue, the selectors could be wrapped in `{}` to clearly isolate them.

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Received on Saturday, 2 February 2019 21:11:56 UTC