VLC feedback: explicitly list CSS features supported in WebVTT

[silviapfeiffer]

Particularly for user agents that do not support CSS, it's important to list all the CSS features that are supported in CSS, particularly in the STYLE element.

[dwsinger]

Not sure I completely understand. There are UAs that don't do CSS; all you get is the basic nuilt-in styling support (which needs to include color, and currently has stuff like ). There are UAs that do support CSS, and I suppose we could list the CSS that they need to support (2.1?), but should we?

[silviapfeiffer]

There are some css selectors that are allowed to be applied to cues and spans. We should give non CSS user agents a chance to implement those for use inside the STYLE tag. But we need to list them more explicitly in the format section and take out of the rendering section.

[dwsinger]

We could say that a non-CSS user-agent may implement selected CSS features, or even should implement simple ones that we mention in the document and list, sure.

[silviapfeiffer]

Yes, indeed 😀