Matlab Uihtml Design

---
name: matlab-uihtml-design
description: Generate beautiful, distinctive HTML/CSS/JS control panels for MATLAB uihtml components. 8 built-in styles (Clean, Material, Cosmic Dark, Neumorphic, Dashboard Light, Midnight Gradient, Minimal Mono, Warm Dark) plus custom aesthetics. Produces production-grade UI with sliders, buttons, toggles, and panels. Use when building visually polished MATLAB app UIs with uihtml.
license: MathWorks BSD-3-Clause (see LICENSE)
metadata:
  author: MathWorks
  version: "1.0"
---

# MATLAB uihtml Design Skill

Generate production-grade HTML/CSS/JS control panels for MATLAB `uihtml` components with distinctive, configurable visual styles.

## When to Use

- User wants beautiful custom controls in a MATLAB app via `uihtml`
- User asks for a specific design style (Clean, Material, dark theme, etc.)
- User wants to redesign or restyle existing `uihtml` controls
- User describes a custom aesthetic for their MATLAB app controls

## Style Selection

Built-in styles are documented in `references/design-styles.md`. To apply a style:

1. If the user names a built-in style, read the corresponding file from `references/styles/<name>.md`
2. If the user describes a custom aesthetic, apply creative design thinking (see below) without loading a reference style
3. If no style is specified, **open the visual style gallery** in the user's browser so they can see all 8 styles side-by-side:

   ```bash
   start "" "<skill-directory>/assets/style-gallery.html"   # Windows
   open "<skill-directory>/assets/style-gallery.html"       # macOS
   ```

   Then ask: "I've opened the style gallery in your browser. Which style would you like? You can also describe a custom aesthetic."

   The gallery shows interactive previews of all 8 built-in styles with a Dark/Light toggle. The available styles are:

   | Style | Vibe |
   |-------|------|
   | Clean | Frosted glass, depth layers, spring animations |
   | Material | Tonal surfaces, elevation, rounded shapes |
   | Cosmic Dark | Deep space, neon glow, glassmorphism |
   | Neumorphic Dark | Embossed/debossed, soft shadow pairs |
   | Dashboard Light | White cards, indigo accent, data-dense |
   | Midnight Gradient | Blue-to-purple gradients, luxury glow |
   | Minimal Mono | Ultra-flat, pill buttons, single accent |
   | Warm Dark | Amber/yellow accent, friendly, smart home |

   If the user says "just pick one" or wants to move fast, default to Clean.

Each style reference follows the 9-section DESIGN.md format and provides complete specifications for colors, typography, components, motion, and guardrails.

## Design Thinking

Before generating code, commit to a clear aesthetic direction:

- **Purpose**: What does this control panel do? Who uses it?
- **Tone**: What feeling should the interface evoke?
- **Constraints**: Container size, MATLAB integration requirements, offline (no CDN)
- **Differentiation**: What makes this memorable and cohesive?

Execute the chosen direction with precision. Bold maximalism and refined minimalism both work, as long as the choice is intentional.

## Workflow

1. **Style selection**: Identify or create the aesthetic direction
2. **Component planning**: Determine which controls are needed (sliders, buttons, toggles, etc.)
3. **HTML generation**: Produce self-contained HTML with the chosen style applied
4. **MATLAB integration**: Include `setup(htmlComponent)` boilerplate; defer full MATLAB-side wiring to the `matlab-uihtml-app-builder` skill

## Component Library (v1)

### Sliders
- Range inputs with custom thumb and track styling
- Value display with formatted units
- Horizontal layout with label + value header

### Buttons
- **Primary/Filled**: Bold accent color, prominent shadow/glow
- **Secondary/Outlined**: Transparent with border, subtle hover
- **Destructive/Danger**: Warning color for stop/reset actions
- State: default, hover, active (scale 0.97), disabled

### Toggles
- Sliding toggle switches
- On/off states with color transition
- Accessible click/tap targets

## Theme System

All styles use CSS custom properties for theming. The base architecture:

```css
:root {
    /* Semantic colors, filled by chosen style */
    --color-bg-primary: ...;
    --color-bg-secondary: ...;
    --color-bg-surface: ...;
    --color-accent: ...;
    --color-accent-hover: ...;
    --color-text-primary: ...;
    --color-text-secondary: ...;
    --color-border: ...;

    /* Spacing */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;

    /* Typography */
    --font-family: ...;
    --font-size-sm: ...;
    --font-size-md: ...;
    --font-size-lg: ...;

    /* Radii & Shadows */
    --radius-sm: ...;
    --radius-md: ...;
    --shadow-sm: ...;
    --shadow-md: ...;

    /* Motion */
    --transition-fast: ...;
    --transition-med: ...;
}
```

Support both light and dark modes via `prefers-color-scheme` media query or a `data-theme` attribute on `<html>`:

```css
@media (prefers-color-scheme: dark) { ... }
/* or */
[data-theme="dark"] { ... }
```

## Container-Aware Spacing

`uihtml` containers in MATLAB apps are often height-constrained (e.g., a narrow side panel). When applying any style:

- **Read the existing HTML first** to understand how many controls need to fit
- **Prioritize fitting all controls** over matching the style's ideal spacing. Reduce padding, gaps, and font sizes as needed; the neumorphic effect still works at 16px padding and 16px gaps
- **Use compact variants** when the container holds more than 2 panels: body padding 14px, panel padding 16px, inter-panel gap 16px, button padding 9px 18px
- **Never let content overflow**: if `overflow: hidden` is set on the body, clipped controls are invisible and unusable
- **Test mentally**: count the vertical space budget (panels × padding + gaps + content height) and ensure it fits within a typical side-panel height (~400–500px)

### Scrollable Panels (When Content Exceeds the Container)

When the control set genuinely can't be compacted further (4+ panels, mixed sliders + toggles + buttons), make the panel container scroll instead of clipping. Keep `body` non-scrolling so the background gradient stays anchored, and let the inner `.app` (or whatever you named the flex column) scroll:

```css
html, body {
    overflow: hidden;   /* body never scrolls; background gradient stays put */
}

.app {
    height: 100%;
    overflow-y: auto;
    overflow-x: hidden;
    scrollbar-width: thin;                                    /* Firefox */
    scrollbar-color: rgba(255, 255, 255, 0.12) transparent;   /* Firefox */
}

/* Chromium (uihtml uses CEF/Chromium) */
.app::-webkit-scrollbar { width: 6px; }
.app::-webkit-scrollbar-track { background: transparent; }
.app::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.10);
    border-radius: 3px;
    transition: background var(--t-fast);
}
.app::-webkit-scrollbar-thumb:hover { background: var(--accent-glow); }
```

**Adapt the colors to the chosen palette:**

| Style | Thumb default | Thumb hover |
|---|---|---|
| Dark styles (Cosmic Dark, Midnight, Neumorphic, Warm Dark, Minimal Mono) | `rgba(255,255,255,0.10)` | `var(--accent-glow)` |
| Light styles (Clean, Dashboard Light, Material light mode) | `rgba(0,0,0,0.12)` | `rgba(0,0,0,0.22)` or `var(--accent)` |

Keep the scrollbar `6px` wide and the thumb under 20% alpha; anything heavier breaks the style. Don't show track borders or arrows.

## Conventions

- **Self-contained**: No external CDN links; all CSS and JS inline in a single HTML file
- **Responsive**: Must work within arbitrary `uihtml` container sizes; use flexbox/grid with relative units
- **MATLAB event boilerplate**: Always include the `setup(htmlComponent)` function pattern:

```javascript
function setup(htmlComponent) {
    window.htmlComponent = htmlComponent;

    // Listen for events from MATLAB
    htmlComponent.addEventListener("EventName", function(event) {
        // Handle event.Data
    });

    // Send events to MATLAB
    htmlComponent.sendEventToMATLAB("EventName", { key: value });
}
```

- **Theme sync with MATLAB desktop**: All templates listen for a `SetTheme` event. The MATLAB side can detect the desktop theme and push it to the HTML component. **The `settings` path is R2025a+**, so wrap it in try/catch with a sensible default so the app still works on older releases:

```matlab
% Detect MATLAB desktop theme (R2025a+); fall back to a default on older releases
themeStr = 'dark';   % or 'light', whichever the style is designed for
try
    s = settings;
    themeStr = lower(char(s.matlab.appearance.MATLABTheme.ActiveValue));
catch
    % settings.matlab.appearance not available on this release; keep the default
end

sendEventToHTMLSource(htmlComp, "SetTheme", struct("theme", themeStr));
```

The HTML `setup()` function already includes a `SetTheme` listener that sets `data-theme` on the root element, triggering the CSS variable swap.

- **No generic aesthetics**: Avoid Inter/Roboto/Arial, avoid purple-on-white cliches, avoid cookie-cutter layouts
- **Accessible**: Sufficient color contrast, clear focus states, reasonable touch targets
- **Performance**: CSS-only animations preferred; minimize JavaScript for visual effects
- **External links**: `<a href="…" target="_blank" rel="noopener">` opens in the system default browser from `uihtml`, not inside the MATLAB figure. Useful for "view docs / view source" links in the app header. Style the link to fit the palette (accent color on hover, no underline by default):

  ```css
  .external-link {
      color: var(--text-secondary);
      text-decoration: none;
      transition: color var(--t-fast), text-shadow var(--t-fast);
  }
  .external-link:hover {
      color: var(--accent-secondary);
      text-shadow: 0 0 8px var(--accent-glow);  /* dark styles */
  }
  ```

## Related Skills

- **matlab-uihtml-app-builder**: architecture, communication patterns, event handling, and MATLAB backend integration for uihtml apps. Use it for the functional wiring behind your styled controls.