/* ===== RESET & BASE ===== */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #ffffff;
  --bg-card: rgba(0, 0, 0, 0.025);
  --bg-card-hover: rgba(0, 0, 0, 0.045);
  --surface: #f5f6f8;
  --border: rgba(0, 0, 0, 0.08);
  --text: #3a3f4b;
  --text-muted: #6b7280;
  --accent: #3b5ccc;
  --accent-hover: #2b47a8;
  --accent-glow: rgba(59, 92, 204, 0.1);
  --heading: #111827;
  --radius: 12px;
  --radius-sm: 8px;
  --max-w: 1100px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

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

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

/* ===== UTILITIES ===== */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 100px 0;
  position: relative;
}

.section--alt {
  background: var(--surface);
}

.section__label {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 12px;
  padding: 6px 14px;
  background: var(--accent-glow);
  border-radius: 100px;
}

.section__title {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: 700;
  color: var(--heading);
  margin-bottom: 16px;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.section__subtitle {
  color: var(--text-muted);
  font-size: 1.05rem;
  max-width: 600px;
  line-height: 1.7;
}

.section-header {
  margin-bottom: 48px;
}

.section-header--center {
  text-align: center;
}

.section-header--center .section__subtitle {
  margin: 0 auto;
}

/* ===== NAV ===== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  padding: 0 24px;
  transition: background var(--transition), box-shadow var(--transition);
  background: transparent;
}

.nav.scrolled {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 1px 0 var(--border);
}

.nav__inner {
  max-width: var(--max-w);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.nav__brand {
  font-size: 1.15rem;
  font-weight: 700;
  color: #fff !important;
  letter-spacing: -0.01em;
  transition: color var(--transition);
}

.nav.scrolled .nav__brand {
  color: var(--heading) !important;
}

.nav__links {
  display: flex;
  gap: 8px;
  list-style: none;
}

.nav__links a {
  color: rgba(255, 255, 255, 0.8);
  font-size: 0.85rem;
  font-weight: 500;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  transition: all var(--transition);
}

.nav__links a:hover,
.nav__links a.active {
  color: #fff;
  background: rgba(255, 255, 255, 0.15);
}

.nav.scrolled .nav__links a {
  color: var(--text-muted);
}

.nav.scrolled .nav__links a:hover,
.nav.scrolled .nav__links a.active {
  color: var(--heading);
  background: rgba(0, 0, 0, 0.05);
}

.nav__toggle {
  display: none;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.5rem;
  cursor: pointer;
  padding: 8px;
  transition: color var(--transition);
}

.nav.scrolled .nav__toggle {
  color: var(--heading);
}

@media (max-width: 768px) {
  .nav__toggle {
    display: block;
  }

  .nav__links {
    display: none;
    position: absolute;
    top: 72px;
    left: 0;
    right: 0;
    flex-direction: column;
    background: rgba(255, 255, 255, 0.97);
    backdrop-filter: blur(16px);
    padding: 16px 24px;
    border-bottom: 1px solid var(--border);
  }

  .nav__links.open {
    display: flex;
  }

  .nav__links a {
    padding: 12px 0;
  }
}

/* ===== HERO ===== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  position: relative;
  overflow: hidden;
  padding: 120px 24px 80px;
}

.hero__bg {
  position: absolute;
  inset: 0;
  background: url('../images/hero_image_bg_ur2.png') center/cover no-repeat;
  filter: brightness(0.55) saturate(0.8);
  transform: scale(1.05);
}

.hero__overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.15) 0%, rgba(255, 255, 255, 0.92) 100%);
}

.hero__content {
  position: relative;
  z-index: 2;
}

.hero__greeting {
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.08em;
  margin-bottom: 16px;
  opacity: 0;
  animation: fadeUp 0.8s 0.2s forwards;
  text-shadow: 0 1px 8px rgba(255, 255, 255, 0.5);
}

.hero__name {
  font-size: clamp(2.4rem, 6vw, 4rem);
  font-weight: 800;
  color: var(--heading);
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 16px;
  opacity: 0;
  animation: fadeUp 0.8s 0.4s forwards;
}

.hero__tagline {
  font-size: clamp(1rem, 2vw, 1.2rem);
  color: var(--text);
  max-width: 520px;
  margin: 0 auto 32px;
  line-height: 1.7;
  opacity: 0;
  animation: fadeUp 0.8s 0.6s forwards;
}

.hero__scroll {
  opacity: 0;
  animation: fadeUp 0.8s 0.8s forwards;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 500;
  transition: color var(--transition);
}

.hero__scroll:hover {
  color: var(--accent);
}

.hero__scroll-icon {
  width: 24px;
  height: 38px;
  border: 2px solid var(--text-muted);
  border-radius: 12px;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding-top: 6px;
}

.hero__scroll-dot {
  width: 3px;
  height: 8px;
  background: var(--accent);
  border-radius: 2px;
  animation: scrollPulse 2s infinite;
}

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(24px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes scrollPulse {

  0%,
  100% {
    opacity: 1;
    transform: translateY(0);
  }

  50% {
    opacity: 0.3;
    transform: translateY(6px);
  }
}

/* ===== ABOUT ===== */
.about__grid {
  display: grid;
  grid-template-columns: 300px 1fr;
  gap: 64px;
  align-items: start;
}

.about__photo-wrapper {
  position: relative;
  border-radius: var(--radius);
  overflow: hidden;
  aspect-ratio: 3/4;
}

.about__photo {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.about__photo-wrapper::after {
  content: '';
  position: absolute;
  inset: 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  pointer-events: none;
}

.about__text p {
  margin-bottom: 16px;
  color: var(--text);
}

.about__info {
  list-style: none;
  margin-top: 24px;
  display: grid;
  gap: 12px;
}

.about__info li {
  display: flex;
  gap: 12px;
  font-size: 0.92rem;
}

.about__info-label {
  color: var(--text-muted);
  min-width: 70px;
  font-weight: 600;
  flex-shrink: 0;
}

.about__info-value {
  color: var(--text);
}

.about__actions {
  display: flex;
  align-items: center;
  gap: 20px;
  margin-top: 32px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-size: 0.88rem;
  font-weight: 600;
  transition: all var(--transition);
  cursor: pointer;
  border: none;
}

.btn--primary {
  background: var(--accent);
  color: #fff;
}

.btn--primary:hover {
  background: var(--accent-hover);
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 8px 24px rgba(108, 140, 255, 0.25);
}

.btn--ghost {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
}

.btn--ghost:hover {
  color: var(--heading);
  border-color: rgba(255, 255, 255, 0.2);
  background: rgba(255, 255, 255, 0.04);
}

.social-links {
  display: flex;
  gap: 12px;
  list-style: none;
}

.social-links a {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 1rem;
  transition: all var(--transition);
}

.social-links a:hover {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-glow);
  transform: translateY(-2px);
}

.social-links svg {
  width: 18px;
  height: 18px;
}

@media (max-width: 768px) {
  .about__grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .about__photo-wrapper {
    max-width: 240px;
    margin: 0 auto;
  }
}

/* ===== NEWS CARDS ===== */
.news__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 24px;
}

.news-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: all var(--transition);
}

.news-card:hover {
  background: var(--bg-card-hover);
  border-color: rgba(0, 0, 0, 0.1);
  transform: translateY(-4px);
  box-shadow: 0 16px 48px rgba(0, 0, 0, 0.08);
}

.news-card__img {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.news-card__body {
  padding: 24px;
}

.news-card__title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--heading);
  margin-bottom: 8px;
  line-height: 1.4;
}

.news-card__text {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.7;
}

.news-card__text a {
  font-weight: 600;
}

/* ===== RESEARCH ===== */
.research__content {
  max-width: 760px;
  margin: 0 auto;
  text-align: center;
}

.research__content p {
  color: var(--text);
  font-size: 1.05rem;
  line-height: 1.8;
}

/* ===== PUBLICATIONS ===== */
.pubs__layout {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 48px;
}

.pubs__nav {
  position: sticky;
  top: 88px;
  align-self: start;
}

.pubs__nav ul {
  list-style: none;
}

.pubs__nav li {
  margin-bottom: 4px;
}

.pubs__nav a {
  display: block;
  padding: 10px 16px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-muted);
  border-radius: var(--radius-sm);
  border-left: 2px solid transparent;
  transition: all var(--transition);
}

.pubs__nav a:hover,
.pubs__nav a.active {
  color: var(--heading);
  background: var(--bg-card);
  border-left-color: var(--accent);
}

.pubs__year {
  margin-bottom: 48px;
}

.pubs__year-title {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--heading);
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}

.pub-item {
  padding: 16px 0;
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  transition: background var(--transition);
}

.pub-item:last-child {
  border-bottom: none;
}

.pub-item__title {
  font-weight: 600;
  color: var(--heading);
  font-size: 0.95rem;
  line-height: 1.5;
  margin-bottom: 4px;
}

.pub-item__authors {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 4px;
  line-height: 1.5;
}

.pub-item__journal {
  font-size: 0.85rem;
  font-weight: 600;
}

.pubs__footer {
  margin-top: 32px;
  padding: 20px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  text-align: center;
  font-size: 0.9rem;
  color: var(--text-muted);
}

@media (max-width: 768px) {
  .pubs__layout {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .pubs__nav {
    position: static;
    display: flex;
    overflow-x: auto;
    gap: 4px;
    padding-bottom: 8px;
  }

  .pubs__nav ul {
    display: flex;
    gap: 4px;
    white-space: nowrap;
  }

  .pubs__nav a {
    border-left: none;
    border-bottom: 2px solid transparent;
    padding: 8px 14px;
  }

  .pubs__nav a:hover,
  .pubs__nav a.active {
    border-left-color: transparent;
    border-bottom-color: var(--accent);
  }
}

/* ===== OPEN POSITIONS ===== */
.positions__content {
  max-width: 700px;
}

.positions__content p {
  color: var(--text);
  margin-bottom: 16px;
  line-height: 1.8;
}

/* ===== CONTACT ===== */
.contact__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
}

.contact-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  text-align: center;
  transition: all var(--transition);
}

.contact-card:hover {
  background: var(--bg-card-hover);
  border-color: rgba(0, 0, 0, 0.1);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
}

.contact-card__icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-glow);
  color: var(--accent);
  border-radius: var(--radius-sm);
  font-size: 1.1rem;
  margin: 0 auto 16px;
}

.contact-card__label {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.contact-card__value {
  font-size: 0.88rem;
  color: var(--text);
  line-height: 1.6;
}

.contact-card__value a {
  color: var(--accent);
}

/* ===== FOOTER ===== */
.footer {
  padding: 32px 0;
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
}

.footer a {
  color: var(--text-muted);
  text-decoration: underline;
}

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

/* ===== SCROLL ANIMATIONS ===== */
.reveal {
  opacity: 0;
  transform: translateY(32px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ===== LOADING SCREEN ===== */
.loader {
  position: fixed;
  inset: 0;
  background: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  transition: opacity 0.5s ease;
}

.loader.hidden {
  opacity: 0;
  pointer-events: none;
}

.loader__spinner {
  width: 32px;
  height: 32px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}