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

:root {
  --navy: #1b2a4a;
  --navy-light: #2c3e6b;
  --gold: #b8956a;
  --gold-light: #d4b896;
  --cream: #faf8f5;
  --white: #ffffff;
  --text: #1a1a1a;
  --text-light: #3d3d3d;
  --text-muted: #6a6a6a;
  --border: #e8e4df;
  --font-serif: 'Cormorant Garamond', Georgia, serif;
  --font-sans: 'Inter', -apple-system, sans-serif;
}

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

body {
  font-family: var(--font-sans);
  font-weight: 400;
  color: var(--text);
  background: var(--white);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--navy);
  text-decoration: none;
  border-bottom: 2px solid var(--gold-light);
  transition: color 0.2s, border-color 0.2s;
}

a:hover {
  color: var(--gold);
  border-bottom-color: var(--gold);
}

/* ===== Header ===== */
.site-header {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  z-index: 10;
  padding: 1.5rem 0;
}

.header-inner {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  justify-content: center;
  align-items: center;
}

.site-title {
  font-family: var(--font-serif);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--white);
  letter-spacing: 0.02em;
  border-bottom: none;
}

.site-title:hover {
  color: var(--gold-light);
}

.site-nav {
  display: flex;
  gap: 2rem;
}

.nav-link {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.85);
  border-bottom: none;
  padding-bottom: 0.25rem;
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gold);
  transition: width 0.3s ease;
}

.nav-link:hover,
.nav-link.active {
  color: var(--white);
  border-bottom: none;
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

/* ===== Hero ===== */
.hero {
  position: relative;
  min-height: 320px;
  background: linear-gradient(135deg, var(--navy) 0%, #0f1b33 50%, #1a3a5c 100%);
  background-size: cover;
  background-position: center;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(184, 149, 106, 0.12) 0%, transparent 70%);
  border-radius: 50%;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -30%;
  left: -10%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(184, 149, 106, 0.08) 0%, transparent 70%);
  border-radius: 50%;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  background: linear-gradient(
    to bottom,
    rgba(27, 42, 74, 0.3) 0%,
    rgba(15, 27, 51, 0.6) 100%
  );
}

.hero-content {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 1rem 2rem 2.5rem;
  max-width: 900px;
}

.hero-title {
  font-family: var(--font-serif);
  font-size: 3.4rem;
  font-weight: 700;
  color: var(--white);
  letter-spacing: 0.01em;
  margin-bottom: 0.6rem;
}

.hero-subtitle {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 400;
  color: var(--gold);
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

/* ===== Bio Section ===== */
.bio-section {
  display: flex;
  gap: 2rem;
  align-items: flex-start;
  margin-bottom: 2rem;
}

.bio-photo {
  width: 160px;
  height: 160px;
  border-radius: 50%;
  object-fit: cover;
  flex-shrink: 0;
  border: 3px solid var(--border);
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.1);
}

.bio-text .bio {
  margin-bottom: 1rem;
}

/* ===== Gold accent bar below hero ===== */
.hero-content::after {
  content: '';
  display: block;
  width: 60px;
  height: 3px;
  background: var(--gold);
  margin: 1.5rem auto 0;
}

/* ===== Main Content ===== */
.content {
  max-width: 740px;
  margin: 0 auto;
  padding: 3.5rem 2rem 5rem;
}

.content h1 {
  font-family: var(--font-serif);
  font-size: 2.2rem;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: 1.5rem;
}

.content h2 {
  font-family: var(--font-serif);
  font-size: 1.7rem;
  font-weight: 700;
  color: var(--navy);
  margin-top: 3rem;
  margin-bottom: 1.25rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--gold);
}

.content h3 {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text);
  margin-top: 2rem;
  margin-bottom: 0.75rem;
}

.content p {
  margin-bottom: 1.25rem;
  color: var(--text-light);
}

.content ul, .content ol {
  margin-bottom: 1.25rem;
  padding-left: 1.5rem;
}

.content li {
  margin-bottom: 0.4rem;
  color: var(--text-light);
}

/* ===== About / Bio Section ===== */
.bio {
  font-size: 1.15rem;
  line-height: 1.85;
  color: var(--text);
  margin-bottom: 2.5rem;
  font-weight: 400;
}

.links-row {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin: 2.5rem 0;
}

.link-btn {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.8rem 1.8rem;
  border: 2px solid var(--navy);
  color: var(--navy);
  border-bottom: 2px solid var(--navy);
  transition: all 0.25s ease;
}

.link-btn:hover {
  background: var(--navy);
  color: var(--white);
  border-color: var(--navy);
  border-bottom-color: var(--navy);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(27, 42, 74, 0.2);
}

.link-btn.primary {
  background: var(--navy);
  color: var(--white);
}

.link-btn.primary:hover {
  background: var(--navy-light);
  border-color: var(--navy-light);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(27, 42, 74, 0.3);
}

.contact-line {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-top: 2.5rem;
  font-weight: 400;
}

.contact-line a {
  color: var(--text);
  font-weight: 500;
}

/* ===== Research Papers ===== */
.paper {
  margin-bottom: 2rem;
  padding: 1.75rem;
  background: var(--cream);
  border-left: 3px solid var(--gold);
  border-radius: 0 6px 6px 0;
  transition: transform 0.2s, box-shadow 0.2s;
}

.paper:hover {
  transform: translateX(4px);
  box-shadow: 0 2px 12px rgba(27, 42, 74, 0.08);
}

.paper-title {
  font-family: var(--font-sans);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 0.35rem;
  line-height: 1.45;
}

.paper-meta {
  font-size: 0.95rem;
  color: var(--text-light);
  margin-bottom: 0.6rem;
  font-style: normal;
  font-weight: 500;
}

.paper-description {
  font-size: 0.95rem;
  color: var(--text-light);
  margin-bottom: 0.75rem;
  line-height: 1.7;
  font-weight: 400;
}

/* ===== Collapsible Abstracts ===== */
.paper-abstract {
  margin: 0.5rem 0 0.75rem;
}

.paper-abstract summary {
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--gold);
  cursor: pointer;
  list-style: none;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}

.paper-abstract summary::-webkit-details-marker {
  display: none;
}

.paper-abstract summary::before {
  content: '▸';
  font-size: 0.85rem;
  transition: transform 0.2s;
}

.paper-abstract[open] summary::before {
  transform: rotate(90deg);
}

.paper-abstract summary:hover {
  color: var(--navy);
}

.paper-abstract p {
  margin-top: 0.6rem;
  font-size: 0.9rem;
  color: var(--text-light);
  line-height: 1.75;
  font-weight: 400;
}

.paper-links {
  display: flex;
  gap: 1.25rem;
  flex-wrap: wrap;
}

.paper-links a {
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--gold);
  border-bottom: none;
  transition: color 0.2s;
}

.paper-links a:hover {
  color: var(--navy);
}

.paper-links a::before {
  content: '→ ';
}

/* ===== Footer ===== */
.site-footer {
  background: var(--cream);
  border-top: 2px solid var(--border);
  padding: 2.5rem 0;
  text-align: center;
}

.footer-inner {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 2rem;
}

.site-footer p {
  font-size: 0.8rem;
  color: var(--text-muted);
  letter-spacing: 0.05em;
  font-weight: 400;
}

/* ===== Responsive ===== */
@media (max-width: 600px) {
  .hero {
    height: 300px;
  }

  .hero-title {
    font-size: 2.4rem;
  }

  .header-inner {
    flex-direction: column;
    gap: 0.75rem;
  }

  .content {
    padding: 2.5rem 1.5rem 4rem;
  }

  .bio-section {
    flex-direction: column;
    align-items: center;
    text-align: center;
  }

  .bio-photo {
    width: 120px;
    height: 120px;
  }

  .links-row {
    flex-direction: column;
  }

  .link-btn {
    text-align: center;
  }

  .paper {
    padding: 1.25rem;
  }
}