The style() condition in @container and if() behaves differently depending on the type of the custom property being queried. If --color is registered with the <color> syntax, and --token is not, but both are assigned the red value, then style(--color: #f00) will be true, and style(--token: #f00) will be false.

Ideally, authors should be able to assign a type for the condition instead of relying on the registration of individual properties. I raised this on a separate issue about function parameter types, and @tabatkins suggested --foo as <type>: val for a syntax. This should also work in a range syntax: 10px < --foo as <length> < 20px.