[Bug 21390] New: [Shadow]: add support for styling shadowDOM contents based on host element

https://www.w3.org/Bugs/Public/show_bug.cgi?id=21390

            Bug ID: 21390
           Summary: [Shadow]: add support for styling shadowDOM contents
                    based on host element
    Classification: Unclassified
           Product: WebAppsWG
           Version: unspecified
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Component Model
          Assignee: dglazkov@chromium.org
          Reporter: sorvell@chromium.org
        QA Contact: public-webapps-bugzilla@w3.org
            Blocks: 14978

It should be possible to style shadowDOM contents based on a selector the host
element matches.

In general, it is common to define a set of theme styles that apply if a given
ancestor selector matches. If nodes within a shadowDOM can be styled
conditionally based on the host element, then shadowDOM can easily support this
design pattern.

At a recent discussion, a ::shadow() pseudo-selector was proposed for this
purpose. It would be used in an @host rule as follows:

@host {  
  /* match .foo shadowDOM nodes inside host elements matching .bar */
  .bar::shadow(.foo) {
    ...
  }
}

The ::shadow() pseudo-selector should also support the :root pseudo-selector to
enable children selectors, for example:

@host {  
  /* match .foo shadowDOM children inside host elements matching .bar */
  .bar::shadow(:root > .foo) {
    ...
  }
}

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Received on Monday, 25 March 2013 19:26:17 UTC