Re: [csswg-drafts] [css-cascade] `revert-layer` keyword in keyframes (#6749)

The issue seem more complicated when we take tree scopes into consideration. For example:

```html
<style>
@keyframes anim {
  from { font-size: 100px }
  to { font-size: revert-layer }
}
#target { animation: anim 5s; }
</style>
<div id="target">
  <template shadowroot="open">
    <style>
    :host { font-size: 200px; }
    </style>
  </template>
</div>
```

Which layer does it revert to? If we strictly follow the cascade sorting order, since there are no more layers in the outer tree scope, the layer below is the shadow DOM style, which is `:host { font-size: 200px; }`. Is this behavior what we want?

I don't have a strong opinion on this, but just feel it's quite unintuitive, so it's better to make sure we agree on what to do.

---

And what if there's a `revert-layer` in an animation created by JS? For example:

```javascript
elem.animate({ fontSize: revert-layer }, 1000);
```

Do we revert to the top author layer, including the inline `style` attribute (treating it as a special layer)?

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Received on Thursday, 21 October 2021 00:48:26 UTC