diff --git a/.changeset/alert-remove-surface.md b/.changeset/alert-remove-surface.md
index ed32bd38d2..fcdd9303e5 100644
--- a/.changeset/alert-remove-surface.md
+++ b/.changeset/alert-remove-surface.md
@@ -10,3 +10,5 @@ The Alert component's background is now driven entirely by its `status` prop. Th
 - <Alert surface="1" status="info" />
 + <Alert status="info" />
 ```
+
+**Affected components:** Alert
diff --git a/.changeset/clean-bags-occur.md b/.changeset/clean-bags-occur.md
index ca7cb06b1a..27986eee24 100644
--- a/.changeset/clean-bags-occur.md
+++ b/.changeset/clean-bags-occur.md
@@ -86,6 +86,6 @@ Update CSS selectors targeting surface data attributes:
 + [data-on-bg='neutral-1'] { ... }
 ```
 
-Note: Provider components use `data-bg` (values: `neutral-1` through `neutral-3`, plus intents). Consumer components use `data-on-bg`, which reflects the parent container's bg directly (no auto-increment).
+Note: Provider components use `data-bg` (values: `neutral-1` through `neutral-3`, plus intents). Consumer components use `data-on-bg`, which reflects the parent container's `bg` directly.
 
 **Affected components:** Box, Button, ButtonIcon, ButtonLink, ToggleButton, Card, Flex, Grid
diff --git a/packages/ui/src/components/Box/Box.tsx b/packages/ui/src/components/Box/Box.tsx
index dc1a8521ea..fb87be9ae1 100644
--- a/packages/ui/src/components/Box/Box.tsx
+++ b/packages/ui/src/components/Box/Box.tsx
@@ -25,7 +25,7 @@ export const Box = forwardRef<HTMLDivElement, BoxProps>((props, ref) => {
     BoxDefinition,
     props,
   );
-  const { classes, as, bgChildren } = ownProps;
+  const { classes, as, childrenWithBgProvider } = ownProps;
 
   return createElement(
     as,
@@ -36,7 +36,7 @@ export const Box = forwardRef<HTMLDivElement, BoxProps>((props, ref) => {
       ...dataAttributes,
       ...restProps,
     },
-    bgChildren,
+    childrenWithBgProvider,
   );
 });
 
diff --git a/packages/ui/src/components/Box/definition.ts b/packages/ui/src/components/Box/definition.ts
index 7c1150c2dc..3837dc8ea4 100644
--- a/packages/ui/src/components/Box/definition.ts
+++ b/packages/ui/src/components/Box/definition.ts
@@ -27,7 +27,7 @@ export const BoxDefinition = defineComponent<BoxOwnProps>()({
   classNames: {
     root: 'bui-Box',
   },
-  bg: { provider: true },
+  bg: 'provider',
   propDefs: {
     as: { default: 'div' },
     bg: { dataAttribute: true },
diff --git a/packages/ui/src/components/Button/definition.ts b/packages/ui/src/components/Button/definition.ts
index 3007064a48..d15ceabd77 100644
--- a/packages/ui/src/components/Button/definition.ts
+++ b/packages/ui/src/components/Button/definition.ts
@@ -29,7 +29,7 @@ export const ButtonDefinition = defineComponent<ButtonOwnProps>()({
     content: 'bui-ButtonContent',
     spinner: 'bui-ButtonSpinner',
   },
-  bg: { consumer: true },
+  bg: 'consumer',
   propDefs: {
     size: { dataAttribute: true, default: 'small' },
     variant: { dataAttribute: true, default: 'primary' },
diff --git a/packages/ui/src/components/ButtonIcon/definition.ts b/packages/ui/src/components/ButtonIcon/definition.ts
index 3750a7f3d9..76f6be68ce 100644
--- a/packages/ui/src/components/ButtonIcon/definition.ts
+++ b/packages/ui/src/components/ButtonIcon/definition.ts
@@ -29,7 +29,7 @@ export const ButtonIconDefinition = defineComponent<ButtonIconOwnProps>()({
     content: 'bui-ButtonIconContent',
     spinner: 'bui-ButtonIconSpinner',
   },
-  bg: { consumer: true },
+  bg: 'consumer',
   propDefs: {
     size: { dataAttribute: true, default: 'small' },
     variant: { dataAttribute: true, default: 'primary' },
diff --git a/packages/ui/src/components/ButtonLink/definition.ts b/packages/ui/src/components/ButtonLink/definition.ts
index d528b90917..c86cb026b5 100644
--- a/packages/ui/src/components/ButtonLink/definition.ts
+++ b/packages/ui/src/components/ButtonLink/definition.ts
@@ -28,7 +28,7 @@ export const ButtonLinkDefinition = defineComponent<ButtonLinkOwnProps>()({
     root: 'bui-ButtonLink',
     content: 'bui-ButtonLinkContent',
   },
-  bg: { consumer: true },
+  bg: 'consumer',
   propDefs: {
     size: { dataAttribute: true, default: 'small' },
     variant: { dataAttribute: true, default: 'primary' },
diff --git a/packages/ui/src/components/Card/Card.module.css b/packages/ui/src/components/Card/Card.module.css
index 5450c1feb4..445873f6ba 100644
--- a/packages/ui/src/components/Card/Card.module.css
+++ b/packages/ui/src/components/Card/Card.module.css
@@ -21,7 +21,6 @@
     display: flex;
     flex-direction: column;
     gap: var(--bui-space-3);
-    background-color: var(--bui-bg-neutral-1);
     border-radius: var(--bui-radius-3);
     padding-block: var(--bui-space-3);
     color: var(--bui-fg-primary);
@@ -30,18 +29,6 @@
     width: 100%;
   }
 
-  .bui-Card[data-on-bg='neutral-1'] {
-    background-color: var(--bui-bg-neutral-2);
-  }
-
-  .bui-Card[data-on-bg='neutral-2'] {
-    background-color: var(--bui-bg-neutral-3);
-  }
-
-  .bui-Card[data-on-bg='neutral-3'] {
-    background-color: var(--bui-bg-neutral-4);
-  }
-
   .bui-CardBody {
     flex: 1;
     min-height: 0;
diff --git a/packages/ui/src/components/Card/Card.tsx b/packages/ui/src/components/Card/Card.tsx
index 4e030fcc4c..e3e4781eac 100644
--- a/packages/ui/src/components/Card/Card.tsx
+++ b/packages/ui/src/components/Card/Card.tsx
@@ -28,6 +28,7 @@ import type {
   CardBodyProps,
   CardFooterProps,
 } from './types';
+import { Box } from '../Box/Box';
 
 /**
  * Card component.
@@ -39,12 +40,18 @@ export const Card = forwardRef<HTMLDivElement, CardProps>((props, ref) => {
     CardDefinition,
     props,
   );
-  const { classes, bgChildren } = ownProps;
+  const { classes, children } = ownProps;
 
   return (
-    <div ref={ref} className={classes.root} {...dataAttributes} {...restProps}>
-      {bgChildren}
-    </div>
+    <Box
+      bg="neutral-auto"
+      ref={ref}
+      className={classes.root}
+      {...dataAttributes}
+      {...restProps}
+    >
+      {children}
+    </Box>
   );
 });
 
diff --git a/packages/ui/src/components/Card/definition.ts b/packages/ui/src/components/Card/definition.ts
index 0fc56b482b..6493d01839 100644
--- a/packages/ui/src/components/Card/definition.ts
+++ b/packages/ui/src/components/Card/definition.ts
@@ -32,7 +32,6 @@ export const CardDefinition = defineComponent<CardOwnProps>()({
   classNames: {
     root: 'bui-Card',
   },
-  bg: { provider: true, consumer: true, defaultBg: 'neutral-auto' },
   propDefs: {
     children: {},
     className: {},
diff --git a/packages/ui/src/hooks/useDefinition/types.ts b/packages/ui/src/hooks/useDefinition/types.ts
index 925172d160..91ebdb8ef5 100644
--- a/packages/ui/src/hooks/useDefinition/types.ts
+++ b/packages/ui/src/hooks/useDefinition/types.ts
@@ -27,21 +27,6 @@ export interface PropDefConfig<T> {
 
 export type UtilityPropKey = keyof typeof utilityClassMap;
 
-/**
- * Configuration for how a component participates in the bg system.
- *
- * - `provider` — calls `useBgProvider`, sets `data-bg`, wraps children in `BgProvider`
- * - `consumer` — calls `useBgConsumer`, sets `data-on-bg`
- * - `defaultBg` — default bg value when no `bg` prop is provided (e.g. `'neutral-auto'`)
- *
- * A component can be provider-only, consumer-only, or both.
- */
-export interface BgConfig {
-  provider?: boolean;
-  consumer?: boolean;
-  defaultBg?: string;
-}
-
 export interface ComponentConfig<
   P extends Record<string, any>,
   S extends Record<string, string>,
@@ -51,19 +36,22 @@ export interface ComponentConfig<
   propDefs: { [K in keyof P]: PropDefConfig<P[K]> };
   // readonly for compatibility with const inference from factory
   utilityProps?: readonly UtilityPropKey[];
-  bg?: BgConfig;
+  /**
+   * How this component participates in the bg system.
+   *
+   * - `'provider'` — calls `useBgProvider`, sets `data-bg`, wraps children in `BgProvider`
+   * - `'consumer'` — calls `useBgConsumer`, sets `data-on-bg`
+   */
+  bg?: 'provider' | 'consumer';
 }
 
 /**
  * Type constraint that validates bg props are present in the props type.
- * - Provider-only components must include 'bg' in their props
- * - Provider+consumer components (e.g. Card) don't need a bg prop (they auto-increment)
- * - Consumer-only components don't need a bg prop
+ * - Provider components must include 'bg' in their props
+ * - Consumer components don't need a bg prop
  */
-export type BgPropsConstraint<P, Bg> = Bg extends { provider: true }
-  ? Bg extends { consumer: true }
-    ? {} // provider+consumer: bg prop is optional (auto-increment via defaultBg)
-    : 'bg' extends keyof P
+export type BgPropsConstraint<P, Bg> = Bg extends 'provider'
+  ? 'bg' extends keyof P
     ? {}
     : {
         __error: 'Bg provider components must include bg in props type.';
@@ -93,11 +81,10 @@ type ResolvedOwnProps<
   [K in keyof PropDefs & keyof P]: ResolvePropType<P[K], PropDefs[K]>;
 };
 
-type ChildrenProps<Bg extends BgConfig | undefined> = Bg extends {
-  provider: true;
-}
-  ? { bgChildren: ReactNode; children?: never }
-  : { children: ReactNode; bgChildren?: never };
+type ChildrenProps<Bg extends 'provider' | 'consumer' | undefined> =
+  Bg extends 'provider'
+    ? { childrenWithBgProvider: ReactNode; children?: never }
+    : { children: ReactNode; childrenWithBgProvider?: never };
 
 type DataAttributeKeys<PropDefs> = {
   [K in keyof PropDefs]: PropDefs[K] extends { dataAttribute: true }
diff --git a/packages/ui/src/hooks/useDefinition/useDefinition.tsx b/packages/ui/src/hooks/useDefinition/useDefinition.tsx
index 15817a754c..d1fe9af96c 100644
--- a/packages/ui/src/hooks/useDefinition/useDefinition.tsx
+++ b/packages/ui/src/hooks/useDefinition/useDefinition.tsx
@@ -36,14 +36,10 @@ export function useDefinition<
 ): UseDefinitionResult<D, P> {
   const { breakpoint } = useBreakpoint();
 
-  // Resolve the effective bg value: use the bg prop if provided,
-  // otherwise fall back to the defaultBg from the bg config
-  const effectiveBg = definition.bg?.provider
-    ? props.bg ?? definition.bg.defaultBg
-    : undefined;
-
   // Provider: resolve bg and provide context for children
-  const providerBg = useBgProvider(effectiveBg);
+  const providerBg = useBgProvider(
+    definition.bg === 'provider' ? props.bg : undefined,
+  );
 
   // Consumer: read parent context bg
   const consumerBg = useBgConsumer();
@@ -74,7 +70,7 @@ export function useDefinition<
       ownPropsResolved[key] = finalValue;
 
       // Skip data-bg for bg prop when the provider path handles it
-      if (key === 'bg' && definition.bg?.provider) continue;
+      if (key === 'bg' && definition.bg === 'provider') continue;
 
       if ((config as any).dataAttribute) {
         // eslint-disable-next-line no-restricted-syntax
@@ -83,17 +79,13 @@ export function useDefinition<
     }
   }
 
-  // Provider-only: set data-bg (provider+consumer components use data-on-bg instead)
-  if (
-    definition.bg?.provider &&
-    !definition.bg?.consumer &&
-    providerBg.bg !== undefined
-  ) {
+  // Provider: set data-bg from the resolved provider bg
+  if (definition.bg === 'provider' && providerBg.bg !== undefined) {
     dataAttributes['data-bg'] = String(providerBg.bg);
   }
 
   // Consumer: set data-on-bg from the parent context
-  if (definition.bg?.consumer && consumerBg.bg !== undefined) {
+  if (definition.bg === 'consumer' && consumerBg.bg !== undefined) {
     dataAttributes['data-on-bg'] = String(consumerBg.bg);
   }
 
@@ -117,10 +109,10 @@ export function useDefinition<
   }
 
   let children: ReactNode | undefined;
-  let bgChildren: ReactNode | undefined;
+  let childrenWithBgProvider: ReactNode | undefined;
 
-  if (definition.bg?.provider) {
-    bgChildren = providerBg.bg ? (
+  if (definition.bg === 'provider') {
+    childrenWithBgProvider = providerBg.bg ? (
       <BgProvider bg={providerBg.bg}>{props.children}</BgProvider>
     ) : (
       props.children
@@ -133,7 +125,9 @@ export function useDefinition<
     ownProps: {
       classes,
       ...ownPropsResolved,
-      ...(definition.bg?.provider ? { bgChildren } : { children }),
+      ...(definition.bg === 'provider'
+        ? { childrenWithBgProvider }
+        : { children }),
     },
     restProps,
     dataAttributes,