EmbeddedForm/index.module.pcss holds only the flex box, the scrolling container and a 16px gap. Every dimension — padding 16px, background transparent, min-height 600px, max-width 528px, margin auto — is a widgetConfig value written as an inline style (the defaults are documented on EmbeddedFormContainerProps, not declared in CSS). Same for the header: only height 48px, padding 0 8px and the gray-6 bottom border are in CSS; background, radius, text colour and border colour are inline props whose defaults are transparent, 0px, --gray-0 and --gray-6. Note the 0px radius default: an embedded header is square even though the tray shell is 15px, because it sits inside the dealer's own card. So design against those defaults but never assume them — a dealer can reshape the whole mount without touching widget CSS.

One line in EmbeddedForm/index.tsx, marked TEMP, swaps two things for the Finance form only: heightKey becomes 'minHeight' (every other form maps the same config value to height), and position becomes 'static' (every other form gets 'relative'). Worth stating plainly because it is the opposite way round from how it is usually described: Finance is the static one. The practical effect is that the Finance mount can grow past its configured height while the others are pinned to it — which matters because the calculator's content height varies with the payment matrix.

Each form portals into a host-page div by id, inside a shadow root (createWidgetShadowDOM), so host CSS cannot reach in — the opposite of the embedded search. A MutationObserver on the body watches for the mount appearing or disappearing, because hosts inject VDP markup after boot; the Finance form additionally reads data-vehicle-vin off its mount and re-points the calculator when the element is replaced. While rendering, the widget flags the host's own element with data-mounted so dealer CSS can key off it. Inside, the content is the ordinary Stepper — or SubmitResult with embedded set, which is exactly why the embedded result drops the next-steps checklist. EmbeddedVehicleDeposit is the smallest of these surfaces: a single DepositButton portalled into #retailing-vehicle-deposit, taking its VIN from the mount's data-vehicle-vin and falling back to the vehicle in context.