Limits of Container Queries with Intrinsic Sizing Dependencies

Direct answer

CSS Container Queries Level 3 does not define a deterministic algorithm for circular intrinsic-size dependencies. When a container's size is determined by children that are themselves styled with @container rules against that same container, the specification defers resolution to user-agent-defined behavior. There is no guaranteed consistent UA behavior, and Level 3 provides no deterministic resolution path for such circular size definitions.

How containment context propagates

A query container is created only when an ancestor opts in with container-type: inline-size or container-type: size. An unqualified @container query consults the nearest opted-in ancestor; container-name consults a named ancestor. The context propagates downward through opted-in containers only. It does not flow from a child back to its parent, and non-query ancestors do not participate.

Likely explanation for interdependent sizing

Many engines evaluate the query against the container size from the previous layout pass, apply query-dependent styles, then settle layout. This can break the cycle, but the settled size, number of layout passes, and stability vary by engine and version. container-type: size considers both axes; inline-size considers the inline axis only, so results are not interchangeable.

Verification for this case

1. Build a minimal page with a content-sized parent using container-type: inline-size and a child whose width changes under an @container rule targeting that parent.
2. Inspect the computed width in Chrome, Firefox, and Safari DevTools and compare settled values.
3. Watch for layout thrashing or different settled sizes across engines.

Assumption: this concerns CSS Container Queries Level 3 in modern browsers, not operating-system containers or unrelated runtimes. Because cyclic resolution is UA-defined and version-sensitive, avoid designing components whose intrinsic size and container-query-selected styles mutually depend. Target browser and container-type value affect which axis and engine behavior to verify.