3. 푸터 컴포넌트
Design a comprehensive footer component:
**Structure** (4-column grid on desktop):
- Column 1: Logo + company description (max 280px) + social icons
- Column 2-3: Link groups (Product, Company, Resources, Legal)
- Column 4: Newsletter signup form
**Styling**:
- Background: slate-900 (#0f172a)
- Text: slate-400 for body, white for headings
- Link hover: white with 150ms transition
- Social icons: 20px, 16px gap, hover scale(1.1)
**Newsletter Form**:
- Input + button inline on desktop
- Input: dark background, subtle border, white text
- Button: Primary accent color, "Subscribe" text
- Success/error states with icon feedback
**Bottom Bar**:
- Border-top: 1px slate-800
- Copyright left, legal links right
- Responsive: stack at 640px
**Responsive Grid**:
- Desktop: 4 columns
- Tablet: 2x2 grid
- Mobile: single column, accordion for link groups
Tech: React + Tailwind CSS