Mockup Builder

Mockup Builder

Create HTML mockups for your project's UI that are constrained to Theme.uss variables and designed for direct translation to Unity UI Toolkit.

Skill type: Rigid — follow exactly.

Before Starting

1. Read references/theme-variables.md for the Theme.uss variable catalog. Freshness check: verify the Last synced date is current. If the project's Theme.uss has been modified since that date, regenerate theme-variables.md from Theme.uss's :root block only (see the Freshness Check instructions in theme-variables.md).
2. Read skills/shared/uss-approximation-patterns.md to understand what CSS effects are achievable in USS and how to approximate those that aren't.
3. Read skills/mock-to-unity/references/css-to-uss-mapping.md, specifically the "CSS Properties Not Available in USS" section, for the hard-block list of features that MUST NOT be used in mockups.
4. Read existing mockups in docs/mockups/ for visual language reference — but note that mockups created before this skill may use hardcoded hex values and lack CSS variables. Use them only to understand the project's visual language (colors, proportions, layout patterns), NOT as CSS architecture exemplars.

Constraints

These are non-negotiable. Every mockup must satisfy all of them.

Theming:

• All colors use CSS custom properties mirroring Theme.uss (e.g., var(--color-bg-base))
• All sizes/spacing use Theme.uss scale variables (--spacing-*, --font-size-*, --radius-*, --border-*)
• No hardcoded hex/rgb values anywhere in CSS. New colors get a new --color-* variable in :root with a comment explaining why
• This ensures players can create and share custom themes
• The :root block is a LOCAL COPY of Theme.uss values for browser rendering. Values MUST match references/theme-variables.md exactly. Do not redefine existing variables with different values. If you need a value that doesn't exist, add a new variable with a descriptive name and document it in the Translation Notes.

Layout:

• Flexbox only. No CSS grid — USS does not support it
• No absolute positioning except for overlay elements (modals, tooltips, context menus)
• No CSS transforms except simple translateY for hover lift effects (these need C# in Unity)

USS Feasibility:

• Hard-blocked: Do not use any CSS feature listed in skills/mock-to-unity/references/css-to-uss-mapping.md under "CSS Properties Not Available in USS." These have no USS equivalent and no viable approximation. This includes but is not limited to: text-shadow, @media queries, display: grid/inline, calc(), clamp(), viewport units (vw/vh/vmin/vmax).
• Allowed with mandatory Translation Notes: The following CSS features CAN be used to communicate design intent but MUST have a corresponding entry in the Translation Notes section documenting the specific USS approximation pattern from skills/shared/uss-approximation-patterns.md:
• box-shadow, linear-gradient, repeating-linear-gradient, ::before/::after, text-transform, transition, cursor (non-standard values), border-style: dashed, letter-spacing in em units, backdrop-filter, animation/@keyframes
• A missing translation note for an allowed-with-notes feature is a quality-gate failure.

Naming:

• BEM class naming that maps to USS selectors (e.g., .talent-node, .talent-node__icon, .talent-node--maxed)
• HTML hierarchy must map 1:1 to the intended VisualElement tree

Output:

• Single self-contained HTML file — no external dependencies
• Save to docs/mockups/-mockup.html

Mockup Structure

Every mockup follows this structure:

1. :root block
   - All CSS variables from Theme.uss used by this mockup
   - Any new variables with explanatory comments

2. Component CSS
   - Uses only var() references, never raw values
   - Flexbox layout only
   - BEM class names

3. HTML structure
   - Class names match USS selector intent
   - Hierarchy maps to VisualElement tree
   - Data-attributes for state variants (data-state="maxed", etc.)

4. Translation Notes (visible footer section)
   - CSS features that need C# equivalents (hover → PointerEnterEvent)
   - Properties known to fail in USS (height in ScrollView)
   - Any new Theme.uss variables this mockup introduces

Translation Notes Section

At the bottom of every mockup, include a visible `` covering:

• Hover/active states: CSS :hover and :active → USS supports these as pseudo-classes. Use USS selectors directly (e.g., .button:hover { background-color: ... }). Do NOT use C# PointerEnterEvent/PointerLeaveEvent for hover styling — that pattern is outdated.
• Text overflow: CSS text-overflow: ellipsis → may need C# truncation logic
• Transitions: CSS transition → need DOTween or manual interpolation
• ScrollView children: Any element inside a scrollable area using height/min-height → must be inline C# (Unity 6 USS bug)
• New variables: List any --color-* or --spacing-* variables not yet in Theme.uss
• Absolute positioning: Document which overlay elements use it and why

What This Skill Does NOT Do

• Push for "bold", "unexpected", or "distinctive" aesthetics — match the project's established visual language
• Use CSS features without USS equivalents (grid, multi-column, custom properties in calc(), etc.)
• Create multi-file mockups — always single HTML file
• Generate Unity code — that is mock-to-unity's job

After Creating the Mockup

1. If a browser is available, open the mockup to verify rendering. Otherwise, review the HTML/CSS source for structural correctness and consistency with the project's visual language.
2. Review the Translation Notes section for completeness
3. Commit the mockup file to git

Quality Gate

This skill produces mockups. When used standalone, invoke crucible:quality-gate after the mockup is created and committed. When used as a sub-skill of build, the parent orchestrator handles gating.

The quality gate reviewer MUST check:

1. USS Feasibility — no hard-blocked CSS features used (reference css-to-uss-mapping.md "CSS Properties Not Available in USS")
2. Translation Notes — every allowed-with-notes feature has a documented USS approximation pattern from skills/shared/uss-approximation-patterns.md
3. :root Value Match — all :root variable values match references/theme-variables.md (after freshness check)
4. Theming Compliance — all values use var() references, no hardcoded hex/rgb values
5. Layout Compliance — flexbox only, BEM naming, HTML hierarchy maps 1:1 to VisualElement tree

Items 1-3 are blocking — they guarantee downstream translation failure if not fixed before proceeding to mock-to-unity.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: raddue
• Source: raddue/crucible
• License: MIT

Install and usage instructions live in the source repository linked above.