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

:root {
  --navy:        #1a2744;
  --navy-light:  #2d3f6e;
  --accent:      #2563eb;
  --accent-bg:   #dbeafe;
  --text:        #1f2937;
  --muted:       #6b7280;
  --bg:          #ffffff;
  --bg-alt:      #f9fafb;
  --border:      #e5e7eb;

  --serif: 'Playfair Display', Georgia, serif;
  --sans:  'Inter', system-ui, sans-serif;

  --max-w:  1100px;
  --r:      8px;
  --sh:     0 1px 3px rgba(0,0,0,.10), 0 1px 2px rgba(0,0,0,.06);
  --sh-md:  0 4px 6px -1px rgba(0,0,0,.10), 0 2px 4px -1px rgba(0,0,0,.06);
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--sans);
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  font-size: 16px;
}

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

/* ===== Navigation ===== */
.nav-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.nav-container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2rem;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-family: var(--serif);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--navy);
  letter-spacing: -.02em;
  text-decoration: none;
}

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

.nav-links a {
  color: var(--muted);
  font-size: .88rem;
  font-weight: 500;
  text-decoration: none;
  transition: color .15s;
}
.nav-links a:hover { color: var(--navy); }

.nav-right {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.lang-switch {
  display: flex;
  align-items: center;
  gap: .35rem;
}
.lang-sep { color: var(--border); font-size: .8rem; }
.lang-btn {
  background: none;
  border: none;
  cursor: pointer;
  font-family: var(--sans);
  font-size: .78rem;
  font-weight: 600;
  letter-spacing: .06em;
  color: var(--muted);
  padding: .2rem .1rem;
  transition: color .15s;
}
.lang-btn:hover  { color: var(--navy); }
.lang-btn.active { color: var(--navy); border-bottom: 2px solid var(--accent); }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav-toggle span {
  display: block;
  width: 24px; height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: all .3s;
}

/* ===== Layout helpers ===== */
.container {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 2rem;
}

.section-hero  { padding: 6rem 0; }
.section-alt   { padding: 5rem 0; background: var(--bg-alt); }
.section-white { padding: 5rem 0; }
.section-dark  { padding: 4rem 0; background: var(--navy); color: #fff; }

.section-title {
  font-family: var(--serif);
  font-size: 2rem;
  color: var(--navy);
  margin-bottom: .4rem;
}
.section-sub {
  color: var(--muted);
  font-size: .95rem;
  margin-bottom: 3rem;
  max-width: 600px;
}
.section-sub a { color: var(--accent); }

/* ===== Hero ===== */
.hero-grid {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 4rem;
  align-items: start;
}

.profile-photo {
  width: 220px; height: 220px;
  border-radius: 50%;
  object-fit: cover;
  object-position: center 12%;
  box-shadow: 0 0 0 4px var(--border), var(--sh-md);
  display: block;
}

.hero-label {
  font-size: .78rem;
  font-weight: 600;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: .4rem;
}
.hero-name {
  font-family: var(--serif);
  font-size: 2.8rem;
  color: var(--navy);
  line-height: 1.1;
  margin-bottom: .2rem;
}
.hero-inst {
  font-size: 1rem;
  color: var(--muted);
  margin-bottom: 1.4rem;
}
.hero-positions {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: .45rem;
  margin-bottom: 1.5rem;
}
.hero-positions li {
  font-size: .88rem;
  color: var(--muted);
  padding-left: 1rem;
  position: relative;
  line-height: 1.4;
}
.hero-positions li::before {
  content: '';
  position: absolute;
  left: 0;
  top: .55em;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--accent);
  opacity: .6;
}

.hero-bio {
  font-size: .97rem;
  line-height: 1.8;
  color: var(--text);
  max-width: 580px;
  margin-bottom: 2rem;
}

.hero-metrics {
  display: flex;
  gap: 2.5rem;
  padding: 1.2rem 0;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  margin-bottom: 1.75rem;
}
.metric { display: flex; flex-direction: column; }
.metric-val {
  font-size: 1.7rem;
  font-weight: 700;
  color: var(--navy);
  font-feature-settings: "tnum";
  line-height: 1.1;
}
.metric-lbl {
  font-size: .7rem;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--muted);
}

.metric-source {
  align-self: flex-end;
  font-size: .7rem;
  color: var(--muted);
  margin-left: auto;
}
.metric-source a { color: var(--muted); text-decoration: underline; }
.metric-source a:hover { color: var(--accent); }

.hero-links { display: flex; flex-wrap: wrap; gap: .6rem; }

.btn {
  display: inline-block;
  padding: .48rem 1.1rem;
  border-radius: var(--r);
  background: var(--navy);
  color: #fff;
  font-size: .82rem;
  font-weight: 500;
  text-decoration: none;
  transition: background .15s;
}
.btn:hover { background: var(--navy-light); text-decoration: none; }


.btn-ghost {
  display: inline-block;
  padding: .42rem 1rem;
  border-radius: var(--r);
  border: 1.5px solid var(--navy);
  color: var(--navy);
  font-size: .8rem;
  font-weight: 500;
  text-decoration: none;
  transition: all .15s;
}
.btn-ghost:hover { background: var(--navy); color: #fff; text-decoration: none; }

/* ===== Research cards ===== */
.cards-4 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(185px, 1fr));
  gap: 1.25rem;
}

.card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 1.6rem;
  box-shadow: var(--sh);
  transition: box-shadow .2s, transform .2s;
}
.card:hover { box-shadow: var(--sh-md); transform: translateY(-2px); }

.card-icon { font-size: 1.6rem; margin-bottom: .9rem; }
.card h3 {
  font-family: var(--serif);
  font-size: 1.05rem;
  color: var(--navy);
  margin-bottom: .4rem;
}
.card p { font-size: .87rem; color: var(--muted); line-height: 1.65; }

/* ===== Publications ===== */
.pub-list { display: flex; flex-direction: column; }

.pub-item {
  display: grid;
  grid-template-columns: 58px 1fr 72px;
  gap: 1.25rem;
  padding: 1.4rem 0;
  border-bottom: 1px solid var(--border);
  align-items: start;
}
.pub-item:first-child { border-top: 1px solid var(--border); }

.pub-year {
  font-size: .82rem;
  font-weight: 600;
  color: var(--muted);
  padding-top: .15rem;
}
.pub-title {
  font-size: .93rem;
  font-weight: 500;
  color: var(--navy);
  line-height: 1.45;
  margin-bottom: .2rem;
}
.pub-meta {
  font-size: .82rem;
  color: var(--muted);
  margin-bottom: .5rem;
}
.pub-tags { display: flex; flex-wrap: wrap; gap: .35rem; }
.tag {
  font-size: .68rem;
  padding: .18rem .55rem;
  background: var(--accent-bg);
  color: var(--accent);
  border-radius: 20px;
  font-weight: 500;
}

.pub-cites { text-align: right; padding-top: .15rem; }
.pub-cites span { display: block; font-size: 1.25rem; font-weight: 700; color: var(--navy); line-height: 1.1; }
.pub-cites small { font-size: .65rem; color: var(--muted); text-transform: uppercase; letter-spacing: .05em; }

/* ===== Materials ===== */
.cards-3 {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.5rem;
}

.mat-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 2rem;
  box-shadow: var(--sh);
  display: flex;
  flex-direction: column;
  gap: .65rem;
  transition: box-shadow .2s, transform .2s;
}
.mat-card:hover { box-shadow: var(--sh-md); transform: translateY(-2px); }

.mat-icon { font-size: 2rem; }
.mat-card h3 {
  font-family: var(--serif);
  font-size: 1.1rem;
  color: var(--navy);
}
.mat-card p { font-size: .87rem; color: var(--muted); line-height: 1.65; flex: 1; }

/* ===== Footer / Contact ===== */
.footer-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  padding-bottom: 3rem;
}

.footer-grid h2 {
  font-family: var(--serif);
  font-size: 1.6rem;
  margin-bottom: 1rem;
}
.footer-grid p {
  font-size: .88rem;
  opacity: .8;
  margin-bottom: .4rem;
  line-height: 1.7;
}
.footer-grid a { color: rgba(255,255,255,.85); }
.footer-grid a:hover { color: #fff; text-decoration: underline; }

.footer-links {
  display: flex;
  flex-direction: column;
  gap: .8rem;
  align-items: flex-end;
  justify-content: center;
}
.footer-links a {
  color: rgba(255,255,255,.7);
  font-size: .88rem;
  font-weight: 500;
  text-decoration: none;
  transition: color .15s;
}
.footer-links a:hover { color: #fff; }

.footer-bar {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 1.5rem 2rem 0;
  border-top: 1px solid rgba(255,255,255,.12);
  font-size: .75rem;
  opacity: .4;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-toggle { display: flex; }

  .nav-links {
    display: none;
    position: absolute;
    top: 64px; left: 0; right: 0;
    background: #fff;
    flex-direction: column;
    padding: 1.25rem 2rem;
    gap: 1rem;
    border-bottom: 1px solid var(--border);
    box-shadow: var(--sh-md);
  }
  .nav-links.open { display: flex; }

  .hero-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
    text-align: center;
  }
  .hero-photo-col { display: flex; justify-content: center; }
  .hero-metrics   { justify-content: center; }
  .hero-links     { justify-content: center; }
  .hero-bio       { margin-left: auto; margin-right: auto; }

  .hero-name { font-size: 2.1rem; }

  .pub-item {
    grid-template-columns: 52px 1fr;
    grid-template-rows: auto auto;
  }
  .pub-cites { grid-column: 2; text-align: left; }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
  .footer-links {
    align-items: flex-start;
    flex-direction: row;
    flex-wrap: wrap;
    gap: 1rem;
  }
}