Re: [WICG/webcomponents] CSS selector to style slots with slotted elements (#936)

I've encountered the need for this many times and I think this would be useful.  However, sometimes, knowing whether the slot is empty or not isn't quite good enough because we want to know if the slot contains **visible** elements.  If only I could have `:hasSlotted(:visible)` 😄 .

The visibility bit aside, I think this should work for the case where there are nested slots.  Ex.

```html
outer-component
   --shadowDOM
      <inner-component>
         <slot name="outer" slot="inner"></slot>
      </inner-component>
      <slot></slot>
      ...

inner-component
   --shadowDOM
      <slot name="inner"></slot>
      ...
```

Given such components, usually I would be interested in the flattened assigned nodes.  That is, I would usually consider the `inner` slot not empty in this case...
```html
<outer-component>
  <div slot="outer">...</div>
   ...
</outer-component>
```
But I _would_ usually consider the `inner` to be empty in this case, even though it contains a `slot`.
```html
<outer-component></outer-component>
```

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/WICG/webcomponents/issues/936#issuecomment-880359220