/* Reset & Base */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --green: #10B981;
  --blue: #3B82F6;
  --purple: #8B5CF6;
  --dark: #1F2937;
  --gray: #6B7280;
  --light-gray: #F9FAFB;
  --white: #FFFFFF;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Inter', sans-serif;
  line-height: 1.7;
  color: var(--dark);
  background: var(--white);
  -webkit-font-smoothing: antialiased;
}

/* Navigation */
nav {
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
  z-index: 100;
  padding: 1rem 0;
}

.nav-content {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-weight: 600;
  font-size: 1.1rem;
  color: var(--dark);
}

.nav-links {
  display: flex;
  gap: 1.5rem;
  align-items: center;
}

.nav-links a {
  color: var(--gray);
  text-decoration: none;
  font-size: 0.95rem;
  transition: color 0.2s;
}

.nav-links a:hover {
  color: var(--green);
}

.cta-nav {
  background: var(--green);
  color: var(--white) !important;
  padding: 0.5rem 1rem;
  border-radius: 6px;
  font-weight: 500;
}

.cta-nav:hover {
  background: #059669;
  color: var(--white) !important;
}

/* Main Content */
main {
  max-width: 720px;
  margin: 0 auto;
  padding: 3rem 1.5rem;
}

article {
  margin-bottom: 4rem;
}

/* Hero */
.hero {
  text-align: center;
  margin: 4rem 0 5rem 0;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  margin-bottom: 1rem;
  line-height: 1.1;
  color: var(--dark);
}

.subtitle {
  font-size: 1.3rem;
  color: var(--gray);
  font-weight: 400;
}

/* Typography */
.content h2 {
  font-size: 2rem;
  font-weight: 600;
  margin: 3rem 0 1.5rem 0;
  letter-spacing: -0.02em;
  color: var(--dark);
}

.content h3 {
  font-size: 1.3rem;
  font-weight: 600;
  margin: 2rem 0 0.75rem 0;
  color: var(--dark);
}

.content p {
  font-size: 1.1rem;
  line-height: 1.8;
  margin-bottom: 1.5rem;
  color: var(--dark);
}

.emphasis {
  font-size: 1.3rem;
  font-weight: 500;
  color: var(--green);
  margin: 2rem 0;
}

/* Features */
.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  margin: 3rem 0;
}

.feature {
  padding: 1.5rem;
  background: var(--light-gray);
  border-radius: 8px;
}

.feature h3 {
  font-size: 1.2rem;
  margin: 0 0 0.5rem 0;
}

.feature p {
  font-size: 1rem;
  margin: 0;
  color: var(--gray);
}

/* Checklist */
.checklist {
  list-style: none;
  margin: 2rem 0;
  padding: 0;
}

.checklist li {
  font-size: 1.1rem;
  padding: 0.5rem 0;
  color: var(--dark);
}

/* Use Cases */
.use-cases {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.use-case {
  padding: 1rem;
  border-left: 3px solid var(--green);
  background: var(--light-gray);
}

.use-case strong {
  display: block;
  margin-bottom: 0.5rem;
  color: var(--dark);
}

.use-case p {
  font-size: 0.95rem;
  margin: 0;
  color: var(--gray);
}

/* Tech Stack */
.tech-stack {
  background: var(--light-gray);
  padding: 2rem;
  border-radius: 8px;
  margin: 3rem 0;
}

.tech-stack h3 {
  margin-top: 0;
  font-size: 1.3rem;
}

.tech-stack p {
  font-size: 1rem;
  margin-bottom: 0.75rem;
}

.tech-stack p:last-of-type {
  margin-bottom: 0;
}

/* Links */
a {
  color: var(--green);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s;
}

a:hover {
  border-bottom-color: var(--green);
}

/* Form */
.signup-form {
  display: flex;
  gap: 0.75rem;
  margin: 2rem 0;
  max-width: 500px;
}

.signup-form input {
  flex: 1;
  padding: 0.875rem 1rem;
  font-size: 1rem;
  border: 2px solid #E5E7EB;
  border-radius: 6px;
  font-family: inherit;
  transition: border-color 0.2s;
}

.signup-form input:focus {
  outline: none;
  border-color: var(--green);
}

.signup-form button {
  padding: 0.875rem 1.5rem;
  background: var(--green);
  color: var(--white);
  border: none;
  border-radius: 6px;
  font-size: 1rem;
  font-weight: 500;
  cursor: pointer;
  font-family: inherit;
  transition: background 0.2s;
  white-space: nowrap;
}

.signup-form button:hover {
  background: #059669;
}

.note {
  font-size: 0.9rem;
  color: var(--gray);
  margin-top: 0.5rem;
}

/* Footer */
footer {
  margin-top: 5rem;
  padding-top: 3rem;
  border-top: 1px solid rgba(0, 0, 0, 0.1);
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 2rem;
}

.footer-left p {
  margin: 0;
}

.footer-left .small {
  font-size: 0.9rem;
  color: var(--gray);
  margin-top: 0.25rem;
}

.footer-links {
  display: flex;
  gap: 1.5rem;
}

.footer-links a {
  color: var(--gray);
  font-size: 0.95rem;
  border: none;
}

.footer-links a:hover {
  color: var(--green);
}

.copyright {
  text-align: center;
  font-size: 0.9rem;
  color: var(--gray);
  margin: 0;
}

/* Responsive */
@media (max-width: 768px) {
  .hero h1 {
      font-size: 2.5rem;
  }
  
  .subtitle {
      font-size: 1.1rem;
  }
  
  .content h2 {
      font-size: 1.6rem;
  }
  
  .content p {
      font-size: 1.05rem;
  }
  
  .nav-content {
      flex-direction: column;
      gap: 1rem;
  }
  
  .features,
  .use-cases {
      grid-template-columns: 1fr;
  }
  
  .signup-form {
      flex-direction: column;
  }
  
  .footer-content {
      flex-direction: column;
      gap: 1.5rem;
  }
  
  main {
      padding: 2rem 1.5rem;
  }
}

@media (max-width: 480px) {
  .hero {
      margin: 2rem 0 3rem 0;
  }
  
  .hero h1 {
      font-size: 2rem;
  }
  
  .nav-links {
      gap: 1rem;
      font-size: 0.9rem;
  }
}