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Re: [css-scoping] What is the specificity of :host, :host(), and :host-context()?

From: Philip Walton <philip@philipwalton.com>
Date: Mon, 1 Dec 2014 15:35:02 -0800
Message-ID: <CAGRhNhUJqciVkv4SqPHJ8fkT8N7xW2Rp=cJs9YRPjk+T-orMaQ@mail.gmail.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: www-style list <www-style@w3.org>
> Per <http://dev.w3.org/csswg/css-scoping/#cascading>, rules from outside a
> shadow tree always win against rules within a shadow tree, when they
> attempt to style the same element.

Hmmm, then it seems like there may be a bug in blink. In my example, the
selector `:host(element-name)` wins over the universal selector. Should
that not be the case?








On Mon, Dec 1, 2014 at 3:06 PM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:

> On Fri, Nov 28, 2014 at 5:35 PM, Philip Walton <philip@philipwalton.com>
> wrote:
> > I've put together a demo (working in Chrome), and in each of the three
> > examples, the text is red. It seems to me like it shouldn't be red, but
> > perhaps I'm not clear on the specificity of the host and host-context
> > selectors.
> >
> > http://jsbin.com/tacidonere/1/edit?html,output
> >
> > The gist of the demo is that given the following rule in the <head>
> >
> > * {
> >   color: red;
> > }
> >
> > And the following rule in a shadow root:
> >
> > :host {
> >   color: blue;
> > }
> >
> > It's surprising to me that the universal selector "wins". I was under the
> > impression that pseudo-classes carried the same specificity as regular
> > classes. Is there an exception inside shadow DOM?
> >
> > FWIW, I can see this being a pretty big problem since a lot of CSS resets
> > use the universal selector, and in such cases the various :host selectors
> > will be essentially useless or have to resort to !important.
>
> The specificity is standard for pseudo-classes, but this case is
> actually covered by something higher in the cascade.  Per
> <http://dev.w3.org/csswg/css-scoping/#cascading>, rules from outside a
> shadow tree always win against rules within a shadow tree, when they
> attempt to style the same element.
>
> The fact that styling the host element doesn't mix well with reset
> stylesheets is just yet another entry in the long list of reasons why
> reset stylesheets are the devil. ^_^
>
> ~TJ
>
Received on Monday, 1 December 2014 23:35:29 UTC

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