Re: [shadow-styling] clarify role of the `active shadow tree`

On Fri, Mar 14, 2014 at 10:01 AM, Steve Orvell <sorvell@google.com> wrote:
> This section (http://dev.w3.org/csswg/shadow-styling/#shadow-trees) defines
> the `active shadow tree`, but the spec does not mention the importance this
> has for styling. The spec does say,
>
> "The descendants of a shadow host must not generate boxes as normal.
> Instead, the contents of the active shadow tree generates boxes as if it
> were the contents of the element instead."
>
> It's unclear to me if "generate boxes" is connected with the application of
> a stylesheet. Regardless, the spec needs to clarify the following behavior.

This is me hooking into the in-the-process-of-acquiring-spec-language
concept of the box tree.  Elements generate boxes, which generate
fragments, which are rendered.  If you don't generate boxes, you don't
do anything - this is what display:none does.

On Fri, Mar 14, 2014 at 1:00 PM, Steve Orvell <sorvell@google.com> wrote:
> Upon further reflection, I think it would be better if the `active shadow
> tree` and the <shadow> element had *no influence* on whether or not a
> stylesheet applies.
>
> Instead, all stylesheets in all sibling shadowRoots should always apply.

This is what the spec currently says, so that's good.  ^_^

> For
> rules without :host, there would be no detectable change since the styles
> are still scoped to individual shadowRoots. However, there are implications
> for the :host selector since it reaches up to the host element. In
> particular, this means if there's a :host rule in an older shadowRoot, it
> always applies to the host element.
>
> I believe 90% of the time, this will be what the author wants. In the case
> where it's not, the onus is on the author to override the :host styling in
> the younger shadowRoot. This seems like a good tradeoff.

Just to make sure - multiple shadow roots can style the host element,
but they can't style elements in other shadow roots.  Assuming this is
true, then yeah, this is already implied by the spec.

~TJ

Received on Saturday, 15 March 2014 16:50:22 UTC