It’s easier for humans to read/maintain and it’ll look cleaner because the page file stays tiny and focused on flow.

Why separate components win

Scanability: Page shows the story (steps, state). Details live in BusinessCardMock, HeaderMock, AppIconMock.

Reusability: You’ll reuse the same mockups later (pricing, share page, exports) without copy-paste.

Design iteration: Designers/devs can tweak one component and see it update everywhere.

Testability: Each mockup has small, focused props → simpler unit/visual tests.

Performance: You can React.memo each mockup and avoid needless re-renders.

A11y/theming: Centralize alt text, contrast, dark mode rules.

Minimal API (keep it human-simple)
type BrandTokens = {
  name: string;
  palette: {
    primary: string; secondary: string; accent: string; highlight: string;
    neutral: string; surface: string; textLight: string; textDark: string;
  };
  fontFamily: string;
  textSize: number;
  iconUrl?: string | null; // generated SVG url
};

type LayoutOption = "side-by-side" | "top-bottom";

// BusinessCardMock.tsx
export default function BusinessCardMock({ tokens, layout }: { tokens: BrandTokens; layout: LayoutOption }) { /* ... */ }

// HeaderMock.tsx
export default function HeaderMock({ tokens }: { tokens: BrandTokens }) { /* ... */ }

// AppIconMock.tsx
export default function AppIconMock({ tokens }: { tokens: BrandTokens }) { /* ... */ }

File sketch
src/
  components/mockups/
    BusinessCardMock.tsx
    HeaderMock.tsx
    AppIconMock.tsx
  pages/BrandKit/BrandKitPage.tsx

Tiny usage on the page
import BusinessCardMock from "@/components/mockups/BusinessCardMock";
import HeaderMock from "@/components/mockups/HeaderMock";
import AppIconMock from "@/components/mockups/AppIconMock";

const tokens: BrandTokens = { name, palette, fontFamily, textSize, iconUrl: generatedSvgUrl };

<div className="grid md:grid-cols-3 gap-4">
  <BusinessCardMock tokens={tokens} layout={layout} />
  <HeaderMock tokens={tokens} />
  <AppIconMock tokens={tokens} />
</div>