# CSS Architecture Documentation

## Overview

The CV site uses a **modular CSS architecture** based on ITCSS (Inverted Triangle CSS) principles, organized into layers from generic to specific styles. This approach ensures maintainability, scalability, and reduces specificity conflicts.

## Directory Structure

```
static/css/
├── main.css                      # Entry point - imports all modules
├── print.css                     # Print styles (loaded separately with media="print")
├── 01-foundation/                # Base styles, variables, resets
│   ├── _reset.css               # CSS reset/normalize
│   ├── _variables.css           # CSS custom properties (colors, spacing)
│   ├── _typography.css          # Font definitions and text styles
│   └── _themes.css              # Theme variables (light/dark modes)
├── 02-layout/                    # Page structure and grids
│   ├── _container.css           # Container wrapper styles
│   ├── _page.css                # Page layout structure
│   ├── _grid.css                # Grid system
│   └── _paper.css               # CV paper/document styles
├── 03-components/                # UI components
│   ├── _action-bar.css          # Top action bar
│   ├── _sidebar.css             # Skills sidebar
│   ├── _cv-header.css           # CV header section
│   ├── _cv-section.css          # Generic CV sections
│   ├── _experience.css          # Work experience items
│   ├── _projects.css            # Projects section
│   ├── _courses.css             # Courses section
│   ├── _education.css           # Education section
│   └── _languages.css           # Languages section
├── 04-interactive/               # Interactive elements & HTMX patterns
│   ├── _toggles.css             # Toggle switches (theme, length, icons)
│   ├── _tooltips.css            # Tooltip styles
│   ├── _navigation.css          # Hamburger menu & navigation
│   ├── _scroll-behavior.css     # Scroll-based interactions
│   ├── _buttons.css             # Fixed action buttons
│   ├── _modals.css              # Modal dialogs
│   ├── _toasts.css              # Toast notifications
│   └── _zoom-control.css        # Zoom slider control
├── 05-responsive/                # Responsive breakpoints
│   └── _breakpoints.css         # Media queries for all screen sizes
└── 06-effects/                   # Visual effects
    └── _skeleton.css            # Loading skeleton screens

static/dist/                      # Generated by Lightning CSS (gitignored)
├── bundle.css                    # Development bundle
└── bundle.min.css                # Production bundle (minified)
```

## Layer Descriptions

### 01-foundation/ - Base Styles (Most Generic)

**Purpose**: Fundamental styles that affect the entire application.

- **_reset.css**: Normalizes browser defaults for consistency
- **_variables.css**: CSS custom properties (colors, spacing, z-index)
- **_typography.css**: Font families, sizes, line heights
- **_themes.css**: Theme-specific variables (light/dark/clean modes)

**When to edit**: Changing global colors, fonts, or spacing values.

### 02-layout/ - Structure

**Purpose**: Page-level layout and positioning systems.

- **_container.css**: Main wrapper containers
- **_page.css**: Page layout structure (multi-page CV)
- **_grid.css**: Grid system for content organization
- **_paper.css**: CV paper/document styling (cv-short, cv-long classes)

**When to edit**: Adjusting page structure, paper sizes, or grid systems.

### 03-components/ - UI Components

**Purpose**: Reusable UI components specific to CV sections.

Each file contains styles for a specific CV section:
- Visual appearance (colors, borders, spacing)
- Component-specific layouts
- Section-specific icons and imagery

**When to edit**: Styling individual CV sections or components.

### 04-interactive/ - Interactive Elements

**Purpose**: User interactions, HTMX patterns, and dynamic behaviors.

#### _toggles.css (5.9 KB)
- Theme toggles (light/dark/clean)
- Length toggles (short/long CV)
- Icon visibility toggles
- Toggle switch component styles

#### _navigation.css (8.2 KB)
- Hamburger button styling
- Slide-out navigation menu
- Menu items and submenus
- Smooth scrolling behavior
- Pure CSS hover-triggered menus

#### _scroll-behavior.css (5.0 KB)
- Header hide/show on scroll direction
- Back-to-top button
- Info button (bottom-left)
- Scroll-based visual changes

#### _buttons.css (4.7 KB)
- Fixed action buttons:
  - Download button (PDF export)
  - Print-friendly button
  - Keyboard shortcuts button
  - Zoom toggle button
- Mobile horizontal layout
- At-bottom state changes

#### _modals.css (16 KB)
- **Info Modal**: Project details dialog
- **Keyboard Shortcuts Modal**: Shortcut reference
- **PDF Download Modal**: Interactive thumbnail selection
- Native `<dialog>` element styling
- Glassmorphism effects
- Accessibility features

#### _zoom-control.css (6.3 KB)
- Zoom slider (50%-150%)
- Reset button
- Draggable positioning
- Mobile auto-disable
- localStorage persistence

**When to edit**: Adding new interactive features or HTMX swap patterns.

### 05-responsive/ - Responsive Design

**Purpose**: Media queries for different screen sizes.

#### _breakpoints.css (14 KB)
- **Desktop (>1280px)**: Full layout with sidebars
- **Medium (1024-1280px)**: Compact fonts, collapsible sidebars
- **Medium (901-1023px)**: EN/ES labels, icon-only buttons
- **Tablet (≤768px)**: Centered photo, larger touch targets
- **Mobile (≤540px)**: Single-column, hamburger menu only
- **Small Mobile (≤480px)**: Ultra-compact zoom control

**When to edit**: Adjusting responsive behavior at specific breakpoints.

### 06-effects/ - Visual Effects

**Purpose**: Animations, transitions, and loading states.

- **_skeleton.css**: Loading skeleton screens for language transitions

**When to edit**: Adding new animations or loading states.

### print.css - Print Styles (Separate File)

**Purpose**: Print-optimized styles loaded via `<link rel="stylesheet" href="print.css" media="print">`.

**Location**: `static/css/print.css` (at root level, NOT bundled)

**Why separate**:
1. Only loaded when printing (no bundle bloat)
2. Uses `media="print"` for automatic browser handling
3. Special PDF export requirements
4. Independent of theme system

**When to edit**: Adjusting print output or PDF export appearance.

## Import Order (main.css)

The import order follows the ITCSS inverted triangle - from generic to specific:

```css
/* 01 - Foundation (most generic) */
@import './01-foundation/_reset.css';
@import './01-foundation/_variables.css';
@import './01-foundation/_typography.css';
@import './01-foundation/_themes.css';

/* 02 - Layout */
@import './02-layout/_container.css';
@import './02-layout/_page.css';
@import './02-layout/_grid.css';
@import './02-layout/_paper.css';

/* 03 - Components */
@import './03-components/_action-bar.css';
@import './03-components/_sidebar.css';
@import './03-components/_cv-header.css';
@import './03-components/_cv-section.css';
@import './03-components/_experience.css';
@import './03-components/_projects.css';
@import './03-components/_courses.css';
@import './03-components/_education.css';
@import './03-components/_languages.css';

/* 04 - Interactive */
@import './04-interactive/_toggles.css';
@import './04-interactive/_navigation.css';
@import './04-interactive/_scroll-behavior.css';
@import './04-interactive/_buttons.css';
@import './04-interactive/_modals.css';
@import './04-interactive/_zoom-control.css';

/* 05 - Responsive */
@import './05-responsive/_breakpoints.css';

/* 06 - Effects */
@import './06-effects/_skeleton.css';

/* NOTE: print.css is loaded separately in HTML with media="print" */
```

⚠️ **IMPORTANT**: Do not change the import order. Later imports can override earlier ones based on specificity.

## CSS Bundling (Lightning CSS)

For production, CSS files are bundled and minified using [Lightning CSS](https://lightningcss.dev/) for better performance.

### Bundle Strategy

| Mode | CSS Loading | HTTP Requests |
|------|-------------|---------------|
| Development | Individual files via `@import` | ~27 requests (waterfall) |
| Production | Single bundled file | 1 request |

### Size Comparison

| Metric | Individual Files | Bundle (dev) | Bundle (minified) | Gzip |
|--------|------------------|--------------|-------------------|------|
| Size | 188 KB | 110 KB | 86 KB | ~15 KB |
| Reduction | - | 43% | 54% | 92% |

### Makefile Targets

```bash
# Development: Bundle CSS (readable)
make css-dev

# Production: Bundle + minify CSS
make css-prod

# Watch mode (auto-rebuild on changes)
make css-watch

# Clean generated bundles
make css-clean
```

### Environment-Based Loading

The template conditionally loads CSS based on `GO_ENV`:

```html
<!-- In templates/index.html -->
{{if .IsProduction}}
<link rel="stylesheet" href="/static/dist/bundle.min.css">
{{else}}
<link rel="stylesheet" href="/static/css/main.css">
{{end}}
<!-- Print always separate -->
<link rel="stylesheet" href="/static/css/print.css" media="print">
```

### Build Requirements

```bash
# Install Lightning CSS CLI globally
npm install -g lightningcss-cli

# Verify installation
lightningcss --version
```

### CI/CD Integration

Production builds should run `make css-prod` before deployment:

```yaml
# Example GitHub Actions
- name: Build CSS
  run: make css-prod
```

## File Naming Conventions

- **Prefix with underscore**: `_filename.css` indicates a partial file (imported by main.css)
- **Lowercase with hyphens**: `_action-bar.css` (not `_ActionBar.css` or `_action_bar.css`)
- **Descriptive names**: File name should clearly indicate its purpose

## HTMX Integration

### Interactive Elements Design

The 04-interactive layer is designed to work seamlessly with HTMX patterns:

1. **Atomic Swaps**: Each component can be swapped independently
2. **Out-of-Band Updates**: Modals and toggles support `hx-swap-oob`
3. **Loading States**: Skeleton screens for async content transitions
4. **Progressive Enhancement**: CSS-first approach with JavaScript fallbacks

### Common HTMX Patterns

```html
<!-- Toggle with out-of-band swap -->
<div hx-post="/toggle/theme"
     hx-target=".cv-container"
     hx-swap="outerHTML">
  <!-- Content updated by server -->
</div>

<!-- Modal trigger -->
<button onclick="document.getElementById('pdf-modal').showModal()">
  Download PDF
</button>

<!-- Navigation with smooth scroll -->
<a href="#experience" class="menu-item">
  Experience
</a>
```

## Best Practices

### 1. Single Responsibility Principle
Each CSS file should have one clear purpose. Don't mix concerns.

✅ **Good**: `_buttons.css` contains only button styles
❌ **Bad**: `_buttons.css` contains buttons + modals + forms

### 2. Component Isolation
Components should be self-contained and not depend on parent context.

✅ **Good**:
```css
.modal-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
}
```

❌ **Bad**:
```css
.modal .close {  /* Requires .modal parent */
  position: absolute;
}
```

### 3. Mobile-First Responsive Design
Write mobile styles first, then add desktop enhancements.

✅ **Good**:
```css
.button { padding: 0.5rem; }

@media (min-width: 768px) {
  .button { padding: 1rem; }
}
```

### 4. CSS Custom Properties for Theming
Use variables for theme-specific values.

✅ **Good**:
```css
.button { background: var(--primary-color); }
```

❌ **Bad**:
```css
.button { background: #27ae60; }
```

### 5. Avoid Deep Nesting
Keep specificity low for easier overrides.

✅ **Good**: `.menu-item { }`
❌ **Bad**: `.navigation .menu .item { }`

## Adding New Styles

### Adding a New Component

1. Create new file in `03-components/`:
   ```bash
   touch static/css/03-components/_my-component.css
   ```

2. Add import to `main.css` in the components section:
   ```css
   @import './03-components/_my-component.css';
   ```

3. Write component styles:
   ```css
   /* My Component - Description */
   .my-component {
     /* Styles here */
   }
   ```

### Adding a New Interactive Pattern

1. Determine if it fits an existing file or needs a new one
2. If new file needed, create in `04-interactive/`:
   ```bash
   touch static/css/04-interactive/_my-feature.css
   ```

3. Add import to `main.css` after other interactive files
4. Document HTMX integration patterns if applicable

### Adding Responsive Styles

1. Add media queries to `05-responsive/_breakpoints.css`
2. Group by breakpoint, not by component
3. Use min-width for mobile-first approach

## Performance Considerations

### File Sizes (Production Bundle)
- **Production CSS**: 86 KB minified (~15 KB gzip)
- **Print CSS**: 18 KB (loaded only when printing)
- **Development CSS**: ~188 KB across 27 files

### Production Optimizations
1. **Lightning CSS bundling**: Combines all CSS into single file
2. **Minification**: Removes whitespace, comments, shortens values
3. **Single HTTP request**: Eliminates waterfall from @import
4. **Gzip compression**: 92% network transfer reduction

### Development Workflow
1. **Hot reload friendly**: Individual files for debugging
2. **Browser DevTools**: Can trace styles to source files
3. **Faster iteration**: No build step required
4. **Modular organization**: Easy to find and edit specific styles

## Troubleshooting

### Styles Not Applying

1. **Check import order**: Later imports override earlier ones
2. **Check specificity**: Use browser DevTools to see which rule wins
3. **Check file path**: Ensure `@import` path is correct
4. **Clear browser cache**: Hard refresh (Cmd+Shift+R / Ctrl+Shift+F5)

### Modal Not Showing

1. Check if `<dialog>` element is in DOM
2. Verify `.showModal()` is called (not `.show()`)
3. Check z-index conflicts
4. Inspect `::backdrop` styling

### Responsive Issues

1. Check viewport meta tag in HTML:
   ```html
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   ```
2. Test at exact breakpoint values
3. Use browser DevTools responsive mode
4. Check for `!important` overrides

## Migration History

### v1.0 → v2.0 (Current)

**Before** (Monolithic):
- Single `_remaining.css` file: 2,287 lines
- Difficult to navigate and maintain
- High merge conflict risk

**After** (Modular):
- 6 focused files: 2,042 lines total
- Clear separation of concerns
- Better caching and collaboration
- 245 lines saved through organization

**Breaking Changes**: None - CSS is backward compatible

## Future Enhancements

### Planned Improvements
- [ ] CSS Modules for component scoping
- [ ] CSS Container Queries for responsive components
- [ ] View Transitions API for smooth page changes
- [ ] CSS Nesting (when browser support improves)
- [ ] Tailwind CSS integration (optional)

### Considerations
- Keep HTMX-friendly patterns
- Maintain progressive enhancement
- Preserve print stylesheet functionality
- Ensure accessibility standards (WCAG AA)

## References

- **ITCSS**: [Harry Roberts' ITCSS](https://www.xfive.co/blog/itcss-scalable-maintainable-css-architecture/)
- **BEM Naming**: [getbem.com](http://getbem.com/)
- **CSS Custom Properties**: [MDN Web Docs](https://developer.mozilla.org/en-US/docs/Web/CSS/--*)
- **HTMX Patterns**: [htmx.org](https://htmx.org/)

## Contributing

When adding new styles:

1. Follow the established file structure
2. Use CSS custom properties for theme values
3. Write mobile-first responsive styles
4. Test in multiple browsers
5. Document complex interactions
6. Update this documentation for structural changes

---

**Last Updated**: November 30, 2025
**Version**: 2.1 (Lightning CSS bundling)
**Maintainer**: Development Team