[css-selectors] Support . (dot) notation for non-XHTML namespaces #534
Description
Regarding https://drafts.csswg.org/selectors-4/#class-html
Browsers currently render CSS stylesheets using the .classname (dot notation) differently from the [class~="classname"] notation depending on the node's namespace.
For instance, Firefox treats both cases the same for non-XHTML XML nodes while Chrome only applies the [class~=...] form in http://ffctn.com/doc/chrome-test-style.xml
The issue has been around for a while (see Bugzilla #7758 and Chromium #69444), and boils down to this:
- The spec is clear in saying that dot-notation is meant for (X)HTML nodes
- However, the common practice is that developers prefer/use the dot-notation
- Developers willing to use CSS stylesheets for non-XHTML namespace XML currently can't reliably use the dot-notation because of the different interpretations by browsers
- As a result, one option to do so would be to write the CSS in dot-notation and then transpile it to
[class=~...]notation, which would lead to having either two stylesheets (one per notation) or a default stylesheet in[class=~...]notation instead of the dot-notation.
Given that the dot notation is an alternative syntax to the [class=~...] (at least according to this comment), it would be good if it had the same treatment across all browsers.
Ultimately, I feel XML does not deserve to be treated as a second-class citizen of the web, and would benefit get the same level of tooling support as HTML. Maybe the spec can help by clarifying that if an XML node has a class attribute, then any corresponding dot-notation CSS selector should match?