Build a complete SaaS landing page for a fictional project management tool called "FlowBoard" using Astro.

Requirements:
- Hero section: headline, subheadline, email signup CTA, hero illustration/graphic
- Features section: 6 features with icons and descriptions in a grid
- How It Works section: 3-step process with numbered steps
- Pricing section: 3 tiers (Free, Pro $12/mo, Enterprise $49/mo) with feature comparison
- Testimonials section: 3 customer testimonials with names and roles
- FAQ section: 6 questions with accordion expand/collapse
- Contact form: name, email, message fields with client-side validation
- Navigation: sticky header with smooth scroll to sections, mobile hamburger menu
- Footer: links, social icons, copyright

Technical requirements:
- Astro framework with static site generation
- Responsive design (mobile-first)
- CSS written from scratch — no Tailwind or UI libraries
- Semantic HTML with accessibility (ARIA labels, keyboard navigation)
- Optimized images and lazy loading
- Include tests where applicable
- Include a README with setup instructions
