Foundation

Overlay stacking / z-index

What sits on what

RequiredVisual system
ContractOverlay stacking / z-index
Job
What sits on what
Requirement
must specify
States / rules
Named layers
Specified means
Order written
Hardest context
Publish open + nav shortcut
Example

nav < publish < toast

Counter-example

Three z-50 siblings

How this lives in Building Blocks

Representation: Shared foundation / token / behavior guidance.

Building Blocks should provide shared guidance, semantic roles, examples, and reusable implementation hooks where appropriate. Each product maps those roles to its own theme and documents any justified exceptions.

Do not specify the easy case only.

The source checklist’s hardest-context test is part of what “specified” means: Publish open + nav shortcut.

On-spec signal

nav < publish < toast

Failure signal

Three z-50 siblings

Catalog connection

The product-local Catalog should show this row’s actual state for that product using the Catalog contract. Building Blocks documentation can define the baseline, but it does not make a product’s row Specified, Designed, or In code by itself.

See the Catalog contract →