Tailwind CSS Dark Mode Implementation

I need to implement dark mode for my Tailwind CSS project.

**Current Setup:**
- Tailwind version: [version]
- Framework: [React/Vue/Next.js/etc.]
- Current color usage: [describe]

**Dark Mode Requirements:**
- Toggle method: [button/system preference/both]
- Transition: [smooth/instant]
- Persistence: [localStorage/cookie/none]
- Default: [light/dark/system]

**Design Constraints:**
- Colors must work for both modes: [list key colors]
- Images/illustrations: [need dark variants?]
- Third-party components: [list them]

Please provide:
1. Tailwind config for dark mode
2. Color palette for both modes
3. Toggle component implementation
4. System preference detection
5. Persistence logic
6. Transition effects
7. CSS custom properties approach if beneficial