/* Reset and base styles */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #3b82f6;
  --color-accent: #0891b2;
  --color-text: #1f2937;
  --color-text-light: #4b5563;
  --color-text-muted: #6b7280;
  --color-bg: #ffffff;
  --color-bg-alt: #f9fafb;
  --color-bg-warm: #f3f4f6;
  --color-border: #e5e7eb;
  --color-border-light: #f3f4f6;
  --color-success: #059669;
  --color-white: #ffffff;
  --max-width: 900px;
  --spacing: 1rem;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
  --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.1);
  --transition: 0.2s ease;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.65;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

/* Typography */
h1, h2, h3, h4 {
  line-height: 1.25;
  margin-bottom: var(--spacing);
  color: var(--color-text);
  font-weight: 600;
  letter-spacing: -0.02em;
}

h1 { font-size: 2.5rem; }
h2 { font-size: 1.5rem; }
h3 { font-size: 1.25rem; }

p { margin-bottom: var(--spacing); }

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover {
  color: var(--color-primary-dark);
}

/* Layout */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: calc(var(--spacing) * 3) calc(var(--spacing) * 1.5);
}

/* Header */
.site-header {
  border-bottom: 1px solid var(--color-border);
  padding: var(--spacing) calc(var(--spacing) * 1.5);
}

.site-header .container {
  padding: 0;
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-header .logo {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--color-text);
}

.site-header .logo:hover {
  color: var(--color-primary);
}

.site-header nav ul {
  display: flex;
  list-style: none;
  gap: calc(var(--spacing) * 1.5);
  margin: 0;
  padding: 0;
}

.site-header nav li {
  margin: 0;
}

.site-header nav a {
  color: var(--color-text-light);
  font-weight: 500;
  font-size: 0.95rem;
  transition: color var(--transition);
}

.site-header nav a:hover {
  color: var(--color-primary);
}

/* Hero */
.hero {
  text-align: center;
  padding: calc(var(--spacing) * 4) 0;
  border-bottom: 1px solid var(--color-border);
  margin-bottom: calc(var(--spacing) * 3);
}

.hero h1 {
  margin-bottom: calc(var(--spacing) * 0.5);
}

.hero .tagline {
  font-size: 1.25rem;
  color: var(--color-text-light);
  margin-bottom: calc(var(--spacing) * 1.5);
}

.hero .bio {
  max-width: 600px;
  margin: 0 auto;
  color: var(--color-text-light);
  line-height: 1.7;
}

.social-links {
  display: flex;
  justify-content: center;
  gap: var(--spacing);
  margin-top: calc(var(--spacing) * 1.5);
}

.social-link {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  background: var(--color-bg-warm);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  color: var(--color-text);
  transition: all var(--transition);
}

.social-link:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: var(--color-bg);
}

/* Sections */
section {
  margin-bottom: calc(var(--spacing) * 3);
}

section h2 {
  padding-bottom: var(--spacing);
  margin-bottom: calc(var(--spacing) * 1.5);
  border-bottom: 2px solid var(--color-border-light);
}

/* Projects Grid */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: calc(var(--spacing) * 1.5);
}

.project-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: calc(var(--spacing) * 1.5);
  transition: all var(--transition);
}

.project-card:hover {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.project-card h3 {
  margin-bottom: 0.5rem;
  font-size: 1.1rem;
}

.project-card h3 a {
  color: var(--color-text);
}

.project-card h3 a:hover {
  color: var(--color-primary);
}

.project-card .description {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin-bottom: var(--spacing);
  line-height: 1.6;
}

.project-meta {
  display: flex;
  align-items: center;
  gap: var(--spacing);
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.project-meta .stars {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.project-meta .language {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.language-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  display: inline-block;
}

.language-dot.python { background: #3572A5; }
.language-dot.julia { background: #a270ba; }
.language-dot.javascript { background: #f1e05a; }

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: var(--spacing);
}

.tag {
  background: var(--color-bg-warm);
  padding: 4px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  color: var(--color-text-light);
  border: 1px solid var(--color-border-light);
}

/* Links Section */
.links-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: var(--spacing);
}

.link-card {
  display: flex;
  align-items: center;
  gap: var(--spacing);
  padding: var(--spacing);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

.link-card:hover {
  border-color: var(--color-primary);
  background: var(--color-bg-warm);
}

.link-icon {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-bg-warm);
  border-radius: var(--radius-sm);
  font-size: 1.25rem;
  flex-shrink: 0;
}

.link-info h4 {
  margin: 0 0 0.25rem 0;
  font-size: 0.95rem;
  color: var(--color-text);
}

.link-info p {
  margin: 0;
  font-size: 0.8rem;
  color: var(--color-text-muted);
}

/* Footer */
footer {
  border-top: 1px solid var(--color-border);
  padding: calc(var(--spacing) * 2) calc(var(--spacing) * 1.5);
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

footer p {
  margin: 0;
}

/* Responsive */
@media (max-width: 768px) {
  h1 { font-size: 2rem; }

  .site-header .container {
    flex-direction: column;
    gap: var(--spacing);
  }

  .site-header nav ul {
    gap: var(--spacing);
  }

  .hero {
    padding: calc(var(--spacing) * 2) 0;
  }

  .hero h1 {
    font-size: 1.75rem;
  }

  .hero .tagline {
    font-size: 1.1rem;
  }

  .social-links {
    flex-wrap: wrap;
  }

  .container {
    padding: calc(var(--spacing) * 2) var(--spacing);
  }

  .projects-grid {
    grid-template-columns: 1fr;
  }

  .links-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  h1 { font-size: 1.65rem; }

  .project-meta {
    flex-wrap: wrap;
    gap: 0.5rem;
  }
}

/* Recommendations Grid */
.recommendations-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: calc(var(--spacing) * 1.5);
}

.rec-card {
  display: block;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: calc(var(--spacing) * 1.5);
  transition: all var(--transition);
  text-decoration: none;
}

.rec-card:hover {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.rec-card h3 {
  margin: 0.5rem 0;
  font-size: 1.1rem;
  color: var(--color-text);
}

.rec-card p {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin: 0;
  line-height: 1.6;
}

.rec-badge {
  display: inline-block;
  padding: 3px 10px;
  background: var(--color-bg-warm);
  border: 1px solid var(--color-border);
  border-radius: 20px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
}

.rec-badge.location {
  background: #fef3c7;
  border-color: #fcd34d;
  color: #92400e;
}

.travel-card {
  border-left: 4px solid var(--color-accent);
}

.travel-card:hover {
  border-left-color: var(--color-primary);
}

@media (max-width: 768px) {
  .recommendations-grid {
    grid-template-columns: 1fr;
  }
}