docs: add comprehensive user-oriented PDF export guide

Add detailed, user-friendly documentation for PDF export feature in
CUSTOMIZATION.md to help template users understand and customize
PDF generation.

New Documentation:
- Clear explanation of how PDF export works
- All 4 parameters (lang, length, icons, version) with examples
- Filename convention and patterns
- Frontend integration examples (HTML, HTMX)
- Tips for best PDF results
- Troubleshooting common issues
- Advanced customization guidance

Audience:
- Template users who want to customize their own CV
- Non-technical users who need to understand PDF options
- Developers who want to extend PDF functionality

Examples include:
- Complete URL patterns for all parameter combinations
- Code snippets for frontend buttons
- CSS customizations for print appearance
- Common troubleshooting solutions

doc/7-CUSTOMIZATION.md

@@ -1148,44 +1148,166 @@ func LoadCV(lang string) (*CV, error) {
 {{end}}
 ```
 
-### Custom PDF Styles
+### PDF Export Customization
 
-PDF generation uses same templates but renders with Chromium. Customize print styles:
+The CV site includes a powerful PDF export feature with multiple customization options. Users can download their CV as a PDF with different configurations.
+
+#### How PDF Export Works
+
+When a user clicks "Download PDF", the server:
+1. Takes a snapshot of the CV webpage using headless Chrome
+2. Applies special print-optimized CSS styles (`@media print`)
+3. Generates a professional PDF document
+4. Downloads it with a descriptive filename
+
+#### PDF Export Parameters
+
+The PDF export endpoint accepts 4 parameters that let users customize their PDF:
+
+**1. Language (`lang`)**
+- `en` - English version
+- `es` - Spanish version
+- Default: `en`
+- Example: `/export/pdf?lang=es`
+
+**2. Length (`length`)**
+- `short` - Concise version with summaries only
+- `long` - Detailed version with full descriptions and bullet points
+- Default: `short`
+- Example: `/export/pdf?length=long`
+
+**3. Icons (`icons`)**
+- `show` - Display all company logos, project icons, and visual elements
+- `hide` - Text-only version without icons (more formal)
+- Default: `show`
+- Example: `/export/pdf?icons=hide`
+
+**4. Version (`version`)**
+- `extended` - Full styling with colors and visual elements
+- `clean` - Minimal, print-optimized design
+- Default: `extended`
+- Example: `/export/pdf?version=clean`
+
+#### Example URLs
+
+```bash
+# Short, clean English CV (most compact)
+http://localhost:1999/export/pdf?lang=en&length=short&version=clean
+
+# Long, detailed Spanish CV with all icons
+http://localhost:1999/export/pdf?lang=es&length=long&icons=show&version=extended
+
+# Use defaults (English, short, with icons, extended)
+http://localhost:1999/export/pdf
+```
+
+#### Filename Convention
+
+PDFs are automatically named following this pattern:
+```
+CV-{Your-Name}-{lang}-{length}-{version}.pdf
+```
+
+Examples:
+- `CV-Juan-Andrés-Moreno-Rubio-en-short-clean.pdf`
+- `CV-Jane-Smith-es-long-extended.pdf`
+
+#### Customizing PDF Appearance
+
+PDF appearance is controlled by `@media print` CSS rules. The print styles are already optimized for A4 paper, but you can customize them:
+
+**Location**: `static/css/08-contexts/_print.css` (or your main CSS file)
+
+**Common customizations**:
 
-**Add to `static/css/main.css`**:
 ```css
 @media print {
-    /* PDF-specific styles */
+    /* Change paper size */
-    body {
-        background: white;
-    }
-
-    .cv-page {
-        box-shadow: none;
-        margin: 0;
-    }
-
-    /* Custom PDF header/footer */
     @page {
-        margin: 20mm;
+        size: Letter portrait;  /* US Letter instead of A4 */
-
+        margin: 10mm;           /* Adjust margins */
-        @top-center {
-            content: "Your Name - CV";
     }
 
-        @bottom-right {
+    /* Customize colors */
-            content: "Page " counter(page) " of " counter(pages);
+    .section-title {
-        }
+        color: #000000 !important;  /* Force black text */
     }
 
-    /* Prevent orphans/widows */
+    /* Hide specific elements */
-    p, li {
+    .cv-footer {
-        orphans: 3;
+        display: none !important;
-        widows: 3;
+    }
+
+    /* Adjust font sizes */
+    .cv-name {
+        font-size: 18pt !important;
     }
 }
 ```
 
+#### Frontend Integration
+
+Add a download button to your templates:
+
+```html
+<!-- Simple link -->
+<a href="/export/pdf?lang=en&length=short&version=clean" download>
+    Download PDF
+</a>
+
+<!-- HTMX button (recommended) -->
+<button
+    hx-get="/export/pdf?lang=en&length=short&version=clean"
+    hx-trigger="click">
+    📥 Download Clean PDF
+</button>
+
+<!-- Dynamic button with user's current language -->
+<button
+    hx-get="/export/pdf?lang={{.Lang}}&length=short&version=clean"
+    hx-trigger="click">
+    Download PDF
+</button>
+```
+
+#### Tips for Best PDF Results
+
+1. **Keep it concise**: Use `length=short` for 1-2 page CVs
+2. **Professional look**: Use `version=clean&icons=hide` for formal applications
+3. **Colorful**: Use `version=extended&icons=show` for creative industries
+4. **Test before sharing**: Always preview the PDF before sending to employers
+5. **File size**: Short versions ~1.5-2MB, Long versions ~2-2.5MB
+
+#### Troubleshooting PDF Export
+
+**Problem**: PDF generation times out
+- **Solution**: Reduce content in your JSON files, or increase timeout in `internal/pdf/generator.go`
+
+**Problem**: Fonts look wrong in PDF
+- **Solution**: Ensure fonts are loaded correctly in your HTML head section
+
+**Problem**: Images don't appear in PDF
+- **Solution**: Check that image paths are absolute or relative to server root
+
+**Problem**: Colors are washed out
+- **Solution**: Add `-webkit-print-color-adjust: exact !important;` to your print CSS
+
+#### Advanced: Customizing PDF Generation
+
+If you need more control over PDF generation, you can modify:
+
+**File**: `internal/handlers/cv.go` (ExportPDF function)
+- Add new parameters
+- Change cookie mappings
+- Modify filename pattern
+
+**File**: `internal/pdf/generator.go`
+- Adjust PDF settings (margins, paper size)
+- Change timeout duration
+- Modify chromedp options
+
+See [3-API.md](3-API.md) for complete API documentation.
+
 ### Additional Export Formats
 
 #### Adding Word Export
@@ -1494,7 +1616,7 @@ curl http://localhost:1999/download/pdf?lang=en --output my-cv.pdf
 **CSS changes**:
 ```css
 :root {
-    --accent-blue: #2c3e50;  /* Conservative dark blue */
+    --accent-blue: #013c77;  /* Conservative dark blue */
     --bg-gray: #f4f4f4;      /* Light background */
 }