feat: optimize docs pages and add 4 new doc articles (en + zh)

- Rewrote DocsListPage and DocDetailPage with landing.css aesthetic
  (icon cards, skeleton loader, prose styles, CTA box)
- Added docs-specific CSS to landing.css
- Created image-to-latex, copy-to-word, ocr-accuracy, pdf-extraction
  articles in both English and Chinese
- Updated DocsSeoSection guide cards to link to real doc slugs

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

content/docs/en/ocr-accuracy.md

@@ -0,0 +1,79 @@
+---
+title: OCR Accuracy
+description: Understanding TexPixel recognition accuracy and how to get the best results
+slug: ocr-accuracy
+date: 2026-03-25
+tags: [accuracy, tips]
+order: 5
+---
+
+# OCR Accuracy
+
+TexPixel achieves industry-leading accuracy on mathematical formula recognition — but accuracy isn't uniform across all input types. This guide explains what affects accuracy and how to maximize it.
+
+## Accuracy by Formula Type
+
+| Formula Type | Typical Accuracy |
+|---|---|
+| Printed formulas (textbooks, papers) | 95–99% |
+| Clean handwritten formulas | 88–95% |
+| Scanned documents (300 DPI+) | 93–98% |
+| Photos of whiteboards | 82–92% |
+| Low-resolution images (< 72 DPI) | 60–80% |
+
+These are approximate ranges. Individual results depend heavily on image quality.
+
+## Factors That Affect Accuracy
+
+### Image Quality
+
+The single biggest factor. A blurry, low-resolution, or poorly lit image will always produce worse results than a clean scan.
+
+- **Resolution** — 150 DPI or higher is recommended. 300 DPI is ideal for documents.
+- **Contrast** — dark ink on a white background gives the clearest signal to the model.
+- **Sharpness** — avoid motion blur or out-of-focus shots.
+
+### Formula Complexity
+
+Simple single-line equations are recognized with near-perfect accuracy. More complex structures may have occasional errors:
+
+- Multi-line equation systems
+- Large matrices (6×6 or larger)
+- Heavily nested fractions (3+ levels deep)
+- Non-standard notation or custom symbols
+
+### Handwriting Style
+
+Printed (typed) formulas outperform handwritten ones, but TexPixel handles handwriting well when:
+
+- Letters are clearly formed and not connected (print style, not cursive)
+- Variables are written in distinct sizes (clearly different x and × for example)
+- Spacing between symbols is consistent
+
+### What Reduces Accuracy
+
+- **Rotated images** — formulas at an angle are harder to parse
+- **Overlapping elements** — crossed-out work, annotations, or arrows near symbols
+- **Pencil on paper** — low contrast; try increasing image brightness/contrast before uploading
+- **Multiple formulas in one image** — crop to the specific formula you need
+- **Decorative fonts** — calligraphic or stylized mathematical writing
+
+## Improving Results
+
+If you're getting errors, try these steps in order:
+
+1. **Increase image resolution** — scan at 300 DPI instead of 150 DPI
+2. **Improve contrast** — use a photo editor to increase brightness and contrast
+3. **Crop tightly** — remove surrounding text and whitespace
+4. **Straighten the image** — correct rotation before uploading
+5. **Re-photograph** — better lighting, closer distance, sharper focus
+
+## Reporting Errors
+
+Found a formula type that TexPixel consistently gets wrong? Let us know — accuracy feedback directly improves the model over time.
+
+Contact us at: [support@texpixel.com](mailto:support@texpixel.com)
+
+---
+
+[Upload a formula and test accuracy →](/app)