[css-backgrounds-4] Does background-attachment: fixed work with background-clip: text?

[OnkarRuikar]

On MDN it is mentioned that: [ref]

The background is fixed relative to the viewport. Even if an element has a scrolling mechanism, the background doesn't move with the element. (This is not compatible with background-clip: text.)

Now run this demo on Firefox and Chrome. The background stays fixed in Chrome and not in Firefox.

There is nothing in the spec that says that background-attachment: fixed doesn't work with background-clip: text. Is Chrome correct or Firefox?

From the specifications standpoint, what should happen when the background-attachment: fixed and background-clip: text properties are used together? Should the background remain fixed or scroll?

[SelenIT]

As far as I know, the value text for background-clip is still considered experimental, it doesn't exist at all in the spec you linked to ([css-backgrounds-3]) and was introduced only in [css-backgrounds-4] which is marked "not ready for implementation". There are some useful notes on the history of this value in the related issue. Firefox has "backported" this value for the most popular use cases only. Likely Chrome's behavior is "more correct", but it's hard to file bugs against browsers until this value is specified properly.

[OnkarRuikar]

As far as I know, the value text for background-clip is still considered experimental

But the MDN browser compatibility says it is a standard and not an experimental value. It looks like the text value sneaked in de facto and is not de jure.