/* ========================================
   SINGULAR OPTICS — Design System
   A modern dark-themed academic website
   ======================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600&family=Outfit:wght@300;400;500;600;700&display=swap');

/* ── CSS Custom Properties ── */
:root {
  --bg-primary: #0a0f1a;
  --bg-secondary: #111827;
  --bg-card: rgba(17, 24, 39, 0.7);
  --bg-glass: rgba(17, 24, 39, 0.6);
  --border-glass: rgba(255, 255, 255, 0.08);
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent: #06b6d4;
  --accent-light: #22d3ee;
  --accent-glow: rgba(6, 182, 212, 0.15);
  --gradient-hero: linear-gradient(135deg, rgba(6, 182, 212, 0.12) 0%, rgba(10, 15, 26, 0.95) 50%, rgba(139, 92, 246, 0.08) 100%);
  --gradient-accent: linear-gradient(135deg, #06b6d4, #8b5cf6);
  --shadow-card: 0 4px 30px rgba(0, 0, 0, 0.3);
  --shadow-glow: 0 0 40px rgba(6, 182, 212, 0.1);
  --radius: 12px;
  --radius-lg: 20px;
  --nav-height: 72px;
  --max-width: 1200px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-height) + 20px);
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  font-weight: 300;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6 {
  font-family: 'Outfit', sans-serif;
  font-weight: 500;
  line-height: 1.3;
}

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

a:hover {
  color: var(--accent-light);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* ── Navigation ── */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 clamp(1.5rem, 4vw, 3rem);
  background: var(--bg-glass);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-glass);
  transition: background var(--transition);
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-family: 'Outfit', sans-serif;
  font-weight: 600;
  font-size: 1.1rem;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.nav-logo img {
  height: 36px;
  width: auto;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 0.25rem;
}

.nav-links a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 400;
  padding: 0.5rem 1rem;
  border-radius: 8px;
  transition: all var(--transition);
  position: relative;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.05);
}

.nav-links a.active::after {
  content: '';
  position: absolute;
  bottom: 4px;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 2px;
  background: var(--accent);
  border-radius: 2px;
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 4px;
  background: none;
  border: none;
}

.hamburger span {
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all var(--transition);
}

.hamburger.open span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.hamburger.open span:nth-child(2) {
  opacity: 0;
}

.hamburger.open span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ── Hero Section ── */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: calc(var(--nav-height) + 2rem) 2rem 4rem;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
}

.hero-bg img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: brightness(0.3) saturate(0.7);
}

.hero-bg::after {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--gradient-hero);
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
}

.hero h1 {
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 600;
  letter-spacing: -0.03em;
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, var(--text-primary) 0%, var(--accent-light) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  font-size: clamp(1rem, 1.5vw, 1.15rem);
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* ── Page Header (Non-home pages) ── */
.page-header {
  position: relative;
  padding: calc(var(--nav-height) + 4rem) 2rem 3rem;
  text-align: center;
  overflow: hidden;
}

.page-header::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse at top center, var(--accent-glow) 0%, transparent 60%);
  pointer-events: none;
}

.page-header h1 {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 600;
  letter-spacing: -0.03em;
  margin-bottom: 0.75rem;
}

.page-header p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  max-width: 600px;
  margin: 0 auto;
}

/* ── Container ── */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 clamp(1.5rem, 4vw, 3rem);
}

/* ── Sections ── */
.section {
  padding: 5rem 0;
}

.section-title {
  font-size: clamp(1.5rem, 3vw, 2rem);
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
}

.section-subtitle {
  color: var(--text-secondary);
  font-size: 1rem;
  margin-bottom: 3rem;
}

.section-divider {
  border: none;
  border-top: 1px solid var(--border-glass);
  margin: 0;
}

/* ── Cards ── */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius);
  padding: 2rem;
  transition: all var(--transition);
  backdrop-filter: blur(10px);
}

.card:hover {
  border-color: rgba(6, 182, 212, 0.2);
  box-shadow: var(--shadow-glow);
  transform: translateY(-2px);
}

/* ── Research Sections ── */
.research-block {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: start;
  margin-bottom: 5rem;
  padding-bottom: 5rem;
  border-bottom: 1px solid var(--border-glass);
}

.research-block:last-child {
  border-bottom: none;
  margin-bottom: 0;
  padding-bottom: 0;
}

.research-block.reverse {
  direction: rtl;
}

.research-block.reverse > * {
  direction: ltr;
}

.research-media {
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-card);
  border: 1px solid var(--border-glass);
}

.research-media img,
.research-media video {
  width: 100%;
  display: block;
}

.research-text h3 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
  color: var(--accent-light);
  letter-spacing: -0.01em;
}

.research-text p {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  text-align: justify;
}

.research-refs {
  list-style: none;
  padding: 0;
}

.research-refs li {
  padding: 0.6rem 0;
  padding-left: 1rem;
  border-left: 2px solid rgba(6, 182, 212, 0.3);
  margin-bottom: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  transition: border-color var(--transition);
}

.research-refs li:hover {
  border-left-color: var(--accent);
  color: var(--text-secondary);
}

/* ── Publications ── */
.pub-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.pub-item {
  display: grid;
  grid-template-columns: 1fr auto auto;
  gap: 1.5rem;
  align-items: center;
  padding: 1.25rem 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius);
  transition: all var(--transition);
}

.pub-item:hover {
  border-color: rgba(6, 182, 212, 0.2);
  transform: translateX(4px);
}

.pub-info h3 {
  font-size: 0.95rem;
  font-weight: 500;
  margin-bottom: 0.3rem;
  line-height: 1.4;
}

.pub-info .pub-authors {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 0.15rem;
}

.pub-info .pub-journal {
  font-size: 0.82rem;
  color: var(--text-secondary);
  font-style: italic;
}

.pub-year {
  font-family: 'Outfit', sans-serif;
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 500;
  white-space: nowrap;
}

.pub-citations {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.8rem;
  color: var(--accent);
  background: var(--accent-glow);
  padding: 0.3rem 0.75rem;
  border-radius: 20px;
  white-space: nowrap;
  font-weight: 500;
}

.pub-citations svg {
  width: 14px;
  height: 14px;
}

.pub-stats {
  display: flex;
  gap: 2rem;
  margin-bottom: 3rem;
  flex-wrap: wrap;
}

.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius);
  padding: 1.5rem 2rem;
  text-align: center;
  flex: 1;
  min-width: 140px;
}

.stat-card .stat-number {
  font-family: 'Outfit', sans-serif;
  font-size: 2.5rem;
  font-weight: 700;
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.stat-card .stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-top: 0.25rem;
}

/* ── Gallery ── */
.gallery-grid {
  columns: 3;
  column-gap: 1rem;
}

.gallery-item {
  break-inside: avoid;
  margin-bottom: 1rem;
  border-radius: var(--radius);
  overflow: hidden;
  cursor: pointer;
  position: relative;
  transition: all var(--transition);
}

.gallery-item::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(to top, rgba(0,0,0,0.4) 0%, transparent 50%);
  opacity: 0;
  transition: opacity var(--transition);
  pointer-events: none;
}

.gallery-item:hover::after {
  opacity: 1;
}

.gallery-item:hover {
  transform: scale(1.02);
  box-shadow: var(--shadow-glow);
}

.gallery-item img {
  width: 100%;
  display: block;
  transition: transform var(--transition);
}

/* Lightbox */
.lightbox {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 2000;
  background: rgba(0, 0, 0, 0.95);
  backdrop-filter: blur(20px);
  align-items: center;
  justify-content: center;
  padding: 2rem;
}

.lightbox.active {
  display: flex;
}

.lightbox img {
  max-width: 90vw;
  max-height: 85vh;
  object-fit: contain;
  border-radius: var(--radius);
  box-shadow: 0 0 60px rgba(0, 0, 0, 0.5);
}

.lightbox-close,
.lightbox-prev,
.lightbox-next {
  position: absolute;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: var(--text-primary);
  border-radius: 50%;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition);
  font-size: 1.2rem;
}

.lightbox-close:hover,
.lightbox-prev:hover,
.lightbox-next:hover {
  background: rgba(255, 255, 255, 0.2);
}

.lightbox-close {
  top: 1.5rem;
  right: 1.5rem;
}

.lightbox-prev {
  left: 1.5rem;
  top: 50%;
  transform: translateY(-50%);
}

.lightbox-next {
  right: 1.5rem;
  top: 50%;
  transform: translateY(-50%);
}

/* ── About ── */
.about-content {
  display: grid;
  grid-template-columns: 1fr;
  gap: 3rem;
  max-width: 800px;
  margin: 0 auto;
}

.about-text p {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  text-align: justify;
  font-size: 1.05rem;
}

.timeline {
  position: relative;
  padding-left: 2rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(to bottom, var(--accent), transparent);
}

.timeline-item {
  position: relative;
  padding-bottom: 2rem;
  padding-left: 1.5rem;
}

.timeline-item::before {
  content: '';
  position: absolute;
  left: -2rem;
  top: 0.35rem;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 12px var(--accent);
  transform: translateX(-50%);
  left: -4px;
}

.timeline-item h3 {
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.timeline-item .timeline-place {
  font-size: 0.9rem;
  color: var(--accent);
  margin-bottom: 0.5rem;
}

.timeline-item p {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* ── Contact ── */
.contact-content {
  max-width: 600px;
  margin: 0 auto;
  text-align: center;
}

.contact-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glass);
  border-radius: var(--radius-lg);
  padding: 3rem 2.5rem;
  backdrop-filter: blur(10px);
}

.contact-card h2 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
}

.contact-card p {
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

.contact-email {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 2rem;
  background: var(--accent-glow);
  border: 1px solid rgba(6, 182, 212, 0.3);
  border-radius: 50px;
  color: var(--accent-light);
  font-size: 1.1rem;
  font-weight: 500;
  transition: all var(--transition);
}

.contact-email:hover {
  background: rgba(6, 182, 212, 0.25);
  transform: scale(1.03);
  color: var(--accent-light);
}

.contact-email svg {
  width: 20px;
  height: 20px;
}

.contact-links {
  display: flex;
  gap: 1rem;
  margin-top: 2rem;
  justify-content: center;
  flex-wrap: wrap;
}

.contact-links a {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-glass);
  border-radius: 8px;
  color: var(--text-secondary);
  font-size: 0.85rem;
  transition: all var(--transition);
}

.contact-links a:hover {
  color: var(--text-primary);
  border-color: rgba(6, 182, 212, 0.3);
}

/* ── Footer ── */
.footer {
  padding: 2rem 0;
  border-top: 1px solid var(--border-glass);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.8rem;
}

/* ── Animations ── */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Responsive ── */
@media (max-width: 1024px) {
  .research-block {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
  
  .research-block.reverse {
    direction: ltr;
  }

  .gallery-grid {
    columns: 2;
  }
}

@media (max-width: 768px) {
  .hamburger {
    display: flex;
  }

  .nav-links {
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    bottom: 0;
    flex-direction: column;
    background: var(--bg-secondary);
    padding: 2rem;
    gap: 0.5rem;
    transform: translateX(100%);
    transition: transform var(--transition);
  }

  .nav-links.open {
    transform: translateX(0);
  }

  .nav-links a {
    font-size: 1.1rem;
    padding: 0.75rem 1rem;
  }

  .hero {
    min-height: 80vh;
  }

  .gallery-grid {
    columns: 2;
    column-gap: 0.5rem;
  }

  .gallery-item {
    margin-bottom: 0.5rem;
  }

  .pub-item {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }

  .pub-year, .pub-citations {
    justify-self: start;
  }

  .pub-stats {
    gap: 1rem;
  }

  .contact-card {
    padding: 2rem 1.5rem;
  }
}

@media (max-width: 480px) {
  .gallery-grid {
    columns: 1;
  }
}