design-systems: add 74 brand DESIGN.md files (VoltAgent/awesome-design-md)

- 74 brands: airbnb, stripe, apple, figma, linear, vercel, etc.
- 147 files: DESIGN.md + README.md per brand (~2.1 MB)
- Each DESIGN.md contains structured brand analysis (colors, typography, components)
- Updated 00-overview.md with new design-systems directory

system/css-architecture.md

@@ -0,0 +1,44 @@
+---
+name: system/css-architecture
+title: CSS Architecture Best Practices
+description: Methodologies, file structure, naming conventions.
+tags: [system, css, architecture, bem, oocss]
+source: stripe.com, raycast.com, design-systems.dev, css-tricks.com
+---
+
+# CSS Architecture
+
+## File Structure
+
+```
+css/
+├── tokens/           # Design tokens
+├── base/            # Reset, typography
+├── components/      # Buttons, cards, inputs
+├── layouts/         # Grid, containers
+├── pages/           # Page-specific styles
+└── utilities/       # Helpers
+```
+
+## BEM Naming
+
+```css
+/* Block */
+.card { }
+
+/* Element */
+.card__title { }
+.card__image { }
+
+/* Modifier */
+.card--featured { }
+.card--dark { }
+```
+
+## Anti-patterns
+
+| ❌ Плохо | ✅ Хорошо |
+|----------|-----------|
+| `!important` | BEM specificity |
+| Hardcoded colors | CSS variables |
+| 1000+ line file | Split into modules |