v153 · scroll-axis-lock

Does this browser know the property?

A CSS property that a browser does not recognise is not an error — the declaration is simply dropped, and the page keeps working with the old behaviour. That makes "is it supported?" a question you have to ask deliberately, and answer with the property itself rather than a version number.

Every value, parsed

What the parser accepts, and what it computes to on a real scroll container
valueparses?computes tonote

The invalid rows matter as much as the valid ones. A browser that accepted sideways would not be implementing this property — it would be ignoring the whole declaration, which parses as "accepted" to a careless check. Rejecting what the grammar does not list is the evidence that the grammar is implemented.

Try a value

The property applies to scroll containers, but computed style will happily report a value on anything — an inherited-style question, not a behavioural one. Switching the target shows that the computed value tells you nothing about whether the property will do anything.

see also