No-Theme Contract — same form, same CSS, recolored only via native color fields

Variant D (Bold Outline) rebuilt on the contract: customCSS owns only structure/effect (transparent container, 1.5px outline geometry, 12px radius, 50px height, label + radio insets, uppercase type scale, focus-ring shape). Native FormSetting color tokens own every customer-facing color — title, label, subtext, button background, button text.

Same form + same customCSS (byte-identical, 12,441 chars) — recolored only via native color fields.
Light host native: dark label / dark button
D on light host
Dark host native: white label / white button
D on dark host

What changed between the two: only the native granular color fields — $labelColor #3a3f4a→#ffffff, $titleColor #0e1116→#fff, $subtextColor #737a86→#cbd2dc, $buttonBackgroundColor #1d2128→#ffffff, $buttonTextColor #fff→#111. customCSS was never touched.
Geometry holds: the 1.5px outline border, 12px radius, 50px field height, and the label/radio inset (every label + radio ring begins on one content line just inside the rounded corner) are identical in both — they live in customCSS, not the color fields.
One platform gap: input value text + placeholder + the resting border + the accent (focus ring / required asterisk) have no native token, so they stay as the three documented CSS vars (--embed-ink, --embed-border, --embed-accent). For a true dark host, only --embed-ink needs a one-line CSS change so typed text stays legible — everything else flips natively.