*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --navy: #0f172a;
  --navy-light: #1e293b;
  --navy-mid: #334155;
  --accent: #3b82f6;
  --accent-light: #60a5fa;
  --accent-glow: rgba(59, 130, 246, 0.15);
  --text: #f1f5f9;
  --text-muted: #94a3b8;
  --text-dark: #0f172a;
  --bg-light: #f8fafc;
  --bg-card: #ffffff;
  --border: #e2e8f0;
  --radius: 10px;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
  scroll-padding-top: 72px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
  color: var(--text-dark);
  background: var(--bg-light);
}

img, svg, video {
  max-width: 100%;
  height: auto;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* === Header / Nav === */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: var(--navy);
  border-bottom: 1px solid var(--navy-mid);
  backdrop-filter: blur(12px);
}

.nav-container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -0.02em;
}

.nav-links {
  display: flex;
  align-items: center;
  list-style: none;
  gap: 2rem;
}

.nav-links a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.2s;
}

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

.nav-btn {
  background: var(--accent);
  color: var(--text) !important;
  padding: 0.5rem 1rem;
  border-radius: 6px;
  font-weight: 600 !important;
  transition: background 0.2s !important;
}

.nav-btn:hover {
  background: var(--accent-light) !important;
}

.mobile-menu-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 10px;
}

.mobile-menu-btn span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}

/* === Hero === */

.hero {
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-light) 50%, #1a2744 100%);
  padding: 6rem 1rem 4rem;
  text-align: center;
  color: var(--text);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at 30% 50%, var(--accent-glow) 0%, transparent 50%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  max-width: 1080px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 1rem;
  line-height: 1.1;
}

.subtitle {
  font-size: 1.25rem;
  color: var(--accent-light);
  margin-bottom: 0.75rem;
  font-weight: 500;
}

.hero-detail {
  color: var(--text-muted);
  font-size: 1.05rem;
  margin-bottom: 2rem;
}

.hero-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

.hero-label {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--accent-light);
  margin-bottom: 0.5rem;
}

.instructor-card {
  display: flex;
  gap: 2.5rem;
  align-items: center;
  text-align: left;
  margin: 2rem 0;
  background: white;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
}

.instructor-photo {
  width: 220px;
  height: 220px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--accent);
  flex-shrink: 0;
}

.instructor-info h3 {
  font-size: 1.5rem;
  margin-bottom: 0.25rem;
  color: var(--navy);
}

.instructor-role {
  color: var(--accent);
  font-weight: 600;
  font-size: 1rem;
  margin-bottom: 0.75rem;
}

.instructor-info p {
  color: #475569;
  margin-bottom: 1rem;
  line-height: 1.7;
}

.instructor-highlights {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.instructor-highlights li {
  background: var(--accent-glow);
  color: var(--accent);
  padding: 0.35rem 0.9rem;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
}

/* === Buttons === */

.btn {
  display: inline-block;
  padding: 0.75rem 1.75rem;
  border-radius: 8px;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  transition: transform 0.15s, box-shadow 0.2s, background 0.2s;
  cursor: pointer;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: var(--accent);
  color: white;
  box-shadow: 0 4px 14px rgba(59, 130, 246, 0.3);
  width: 12rem;
}

.btn-primary:hover {
  background: var(--accent-light);
  box-shadow: 0 6px 20px rgba(59, 130, 246, 0.4);
}

.btn-secondary {
  background: transparent;
  color: var(--text);
  border: 2px solid var(--navy-mid);
  width: 12rem;
}

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent-light);
}

/* === Sections === */

.section {
  padding: 5rem 0;
}

.section-alt {
  background: white;
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
}

.section-subtitle {
  text-align: center;
  color: var(--text-muted);
  margin-bottom: 2.5rem;
  font-size: 1rem;
}

/* === Skills === */

.skills-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-top: 2rem;
}

.skill-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  text-align: center;
  transition: box-shadow 0.2s, transform 0.15s;
}

.skill-card:hover {
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}

.skill-icon {
  font-size: 2rem;
  margin-bottom: 0.75rem;
}

.skill-card h3 {
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
  color: var(--navy);
}

.skill-card p {
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* === Projects === */

.projects-list {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  margin-top: 2rem;
}

.project-card {
  background: white;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  border-left: 4px solid var(--accent);
  transition: box-shadow 0.2s;
}

.project-card:hover {
  box-shadow: var(--shadow);
}

.project-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
}

.project-card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--navy);
  flex: 1;
}

.project-tag {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-glow);
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  white-space: nowrap;
}

.project-card p {
  color: #475569;
  font-size: 0.95rem;
  line-height: 1.7;
}

/* === Footer === */

.site-footer {
  background: var(--navy);
  color: var(--text-muted);
  text-align: center;
  padding: 2rem 1.5rem;
  font-size: 0.9rem;
}

.site-footer a {
  color: var(--accent-light);
  text-decoration: none;
  transition: color 0.2s;
}

.site-footer a:hover {
  color: var(--text);
}

/* === Responsive === */

@media (max-width: 900px) {
  .skills-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .nav-container {
    height: auto;
    padding: 0.75rem 1.5rem;
    gap: 1rem;
  }

  .logo {
    font-size: 1.05rem;
  }

  .mobile-menu-btn {
    display: flex;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--navy);
    flex-direction: column;
    padding: 1rem 1.5rem 1.5rem;
    gap: 0.75rem;
    border-bottom: 1px solid var(--navy-mid);
  }

  .nav-links.open {
    display: flex;
  }

  .hero {
    padding: 6rem 1.5rem 3rem;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .subtitle {
    font-size: 1.05rem;
  }

  .section {
    padding: 3rem 0;
  }

  .section-title {
    font-size: 1.6rem;
  }

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

  .instructor-card {
    flex-direction: column;
    text-align: center;
  }

  .instructor-photo {
    width: 140px;
    height: 140px;
  }

  .instructor-info p {
    text-align: left;
  }

  .instructor-highlights {
    justify-content: center;
  }

  .project-card {
    padding: 1.25rem;
  }

  .project-header {
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    text-align: center;
  }

  .project-card h3 {
    flex: none;
  }
}

@media (max-width: 520px) {
  .container {
    padding: 0 1rem;
  }

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

  .hero h3 {
    font-size: 1.5rem;

  }
  .instructor-bio {
    display: none;
  } 

  .instructor-role {
    display: none;
  } 

  .instructor-card {
    margin-top: 0%;
    gap: 0.5rem;
  }

  .section-title {
    font-size: 1.4rem;
  }

  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .btn-primary,
  .btn-secondary {
    width: 100%;
    text-align: center;
  }

  .project-card {
    padding: 1rem;
  }

  .project-card p {
    font-size: 0.9rem;
  }
}