Redesign the entire UI of this application to look like Windows 11 Fluent Design. This is a UI-only redesign - do NOT change any business logic, API routes, database schema, or functionality. Only modify visual styling (CSS classes, Tailwind utilities, color values, border-radius, shadows, etc.).

Changes needed:

1. globals.css - Update theme:
   - Primary color: #0078D4 (Windows 11 blue)
   - Add --color-win11-accent: #0078D4 and shades (#106EBE, #005A9E, #003D6B)
   - Background: light #f3f3f3, dark #202020
   - Rounded corners: 8px cards, 4px small elements
   - Shadows: subtle layered shadows like Win11 (0 2px 8px rgba(0,0,0,0.04), 0 8px 32px rgba(0,0,0,0.08))
   - Smooth transitions: 200-300ms ease
   - Add acrylic utility: .acrylic { backdrop-filter: blur(20px) saturate(180%); background: rgba(255,255,255,0.7); }
   - Add .acrylic-dark for dark mode

2. app/(main)/layout.tsx - Main layout:
   - Background: #f3f3f3 (light) / #202020 (dark)
   - Sidebar: add bg-white/80 dark:bg-[#2d2d2d]/80 backdrop-blur-xl rounded-e-lg
   - Content area: clean with subtle padding

3. components/sidebar.tsx - Windows 11 navigation:
   - Semi-transparent bg with backdrop-blur-xl
   - Nav items: rounded-lg hover states with subtle bg-slate-100 dark:bg-slate-800
   - Active item: bg-blue-50 dark:bg-blue-900/30 text-[#0078D4] with left border-2 indicator
   - Smooth collapse animation with transition-all duration-300

4. components/header.tsx - Windows 11 title bar:
   - Clean minimal, height h-12
   - Rounded search input (rounded-full or rounded-lg) like Win11 search
   - Subtle bottom border

5. components/note-card.tsx - Win11 cards:
   - rounded-lg (8px)
   - border border-slate-200 dark:border-slate-700
   - hover:shadow-lg hover:-translate-y-0.5 transition-all duration-200
   - Clean white bg

6. components/home-client.tsx - Widget layout:
   - Rounded containers (rounded-xl) for each section
   - Subtle hover:shadow-md transition

7. components/note-editor.tsx & rich-text-editor.tsx - Win11 editor:
   - Rounded toolbar buttons (rounded-md)
   - Subtle separators between toolbar groups
   - Clean focused state

8. components/ui/button.tsx - Win11 buttons:
   - rounded-md (6px)
   - Primary: bg-[#0078D4] hover:bg-[#106EBE] text-white
   - Secondary: bg-slate-100 hover:bg-slate-200 border border-slate-300
   - Subtle active states

9. components/ui/card.tsx - Win11 card:
   - rounded-lg border border-slate-200/60
   - hover:shadow-md transition-shadow duration-200

10. components/ui/input.tsx - Win11 input:
    - rounded-md (6px)
    - border-slate-300 focus:border-[#0078D4] focus:ring-1 focus:ring-[#0078D4]/30

Read each file first, understand its structure, then make surgical edits. After all changes, run npm run build to verify the build passes. Fix any build errors if any.