The current draft visual system follows neobrutalism.dev, pinned to neobrutalism-components 3306a802. Proto UI maintains its own implementation and Base semantics; this is not an upstream certification or component API compatibility promise.

DM Sans is the reference default, not universal monospace or forced uppercase. The prototype owns its font role through generated style tokens:

• Ordinary controls, menu items, descriptions and content: font-sans font-medium, DM Sans 500
• Dialog title, Tabs triggers and Toggle: font-heading font-bold, DM Sans 700
• Default labels: 14px/20px; Badge: 12px/16px; Dialog title: 18px with unit line-height and tight tracking
• Preserve authored casing. Code and keyboard notation may use their own mono role

The package theme declares "DM Sans", ui-sans-serif, system-ui, sans-serif through --pui-font-sans and --pui-font-heading. The docs self-host an unmodified variable DM Sans font under SIL OFL 1.1. Application consumers supply their own font loading; prototypes do not make network requests. A missing font uses the system sans fallback. Chinese glyphs use the host CJK fallback, so a Latin font-family declaration alone does not prove the actual font used for every glyph.

• Ordinary controls and panels: 5px rounded-base, 2px black structural border
• Switch track/Thumb and Scroll Area Thumb: full-round geometry; Checkbox stays square
• Tabs List and nested Trigger each own their radius; the inset spacing separates them
• Card Header/Content/Footer and Tabs Content do not create mandatory nested frames
• Scroll Area Root owns rounded overflow clipping; its viewport stays square and the host retains track/Thumb geometry
• Spinner retains its centered circular open ring

Rounded corners are part of this design language. Do not apply a blanket square-corner override or make every inner surface another bordered panel.

The upstream reverse Button variant is separate; the current PUI API does not claim it. Toggle keeps a 2px inset active marker through press as a non-color PUI extension. Base continues to own active versus pressed, selection, keyboard behavior, ARIA and command wiring. Existing popup transitions and Spinner reduced-motion behavior remain intact; Skeleton remains static.

The default follows the reference’s blue palette: main #5294ff, pale blue background #dcebfe, white neutral surfaces, black text and structure. Named PUI accent pairs retain canary, mint, lavender, coral and sky roles with black accent ink. Color supplements labels, position and persistent state signals.

The inspected upstream style registry has no dark palette. Proto UI’s dark paper/panels, light text, readable destructive ink and theme-relative focus ring are explicitly maintained extensions. The same mounted controls repaint from theme variables; a paired foreground is never replaced independently of its fill.

BRUTALIST_THEME is the package-owned source for Light/Dark values, font roles and radii. CLI and docs scopes consume generated projections of the complete manifest. Start a project with proto-ui init --prototypes brutalist; config v1 permits one enabled style preset. With --no-styles, applications supply the required semantic tokens and font loading themselves.

Focus retains a visible offset ring and at least 3:1 adjacent-color contrast. Tabs Content retains native fallback focus indication. Disabled controls retain geometry and Base gates; portaled surfaces retain theme/font variables. PUI uses the reference 24×48px Switch frame and single 20px Thumb movement, Checkbox mixed-state precedence and parent-owned loading semantics.

Adapted component recipes retain the upstream MIT notice, copyright Samuel Breznjak; redistributed DM Sans retains its SIL OFL notice. Current styled criteria remain draft, and visual alignment does not expand native-host support or introduce a new Base subject.

Select placeholders on the main blue fill retain paired black ink rather than neutral muted ink: the latter measures only 2.62:1 in Light and 2.01:1 in Dark. This deliberate readability adaptation must retain at least 4.5:1 text contrast in both modes.

The full DM Sans copyright and OFL license is served alongside this site’s font assets. Textarea retains a theme-foreground border so its editable boundary has at least 3:1 contrast against both adjacent surfaces, including Dark.

Button-like controls currently retain PUI’s instant snap; the reference’s 150ms transition-all is not claimed. Switch owns the measured 150ms Thumb transition separately.