Re: [csswg-drafts] [css-mixins-1] Why do mixins see private properties visible to the style rule it is substituted into? (#14408)

> > Applying a mixin with @apply effectively substitutes the mixin in-place, so a mixin sees any private properties visible to the style rule it’s substituted into (if it doesn’t override them with its own mixin parameters or private properties).
> This seems weird to me. It kinda breaks the entire premise of @private making things private.

I think I initially also interpreted the current spec as implying that mixins could influence private properties outside of themselves.

Basically:

```css
@mixin --a() {
  @private { --foo: 10px; }
}

div { 
  @private { --foo: 2px; }
  @apply --a();
  margin: var(--foo); /* influenced by the mixin and now 10px */
}
```

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Received on Wednesday, 2 September 2026 08:07:39 UTC