(Follow-up on this comment.)

According to this resolution, the @container prelude grammar accepts a list of <container-condition>s:

@container <container-condition># { <block-contents> }

<container-condition> = [ <container-name> ]? <container-query>

But CSSContainerRule.containerQuery and CSSContainerRule.containerName still return a single container query/name.

Can you please tell me if there is any reason to withhold the appropriate changes on the CSSOM? Do you plan to rename the attributes? To remove them? To return a list of strings or a string of comma-separated values?

The current version of Chrome/FF (at least) only accept a single <container-condition>.