custom selectors are pseudo classes

[MoOx]

Should be

@custom-selector :--heading h1, h2, h3, h4, h5, h6;

:--heading { /* styles for all headings */ }
:--heading + p { /* more styles */ }

http://dev.w3.org/csswg/css-extensions/#example-5b616cc6

We need to support that asap and add a warning message to deprecate previous behavior.
I will try to tackle this.

[yisibl]

In the specification may be in order to distinguish and custom property.

@custom-property --foo {
  scope: [ inherit | local ];
  initial: <any-value>*;
  value: <length> <length> <color>;
  /* Literally, define a simplistic definition syntax.
     OR FULL CSS PROPERTY GRAMMAR?!? */
}

[MoOx]

We should warn for custom selector that are NOT using :.

[MoOx]

I guess 2.0 close this ?