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

:root {
  --color-bg: #ffffff;
  --color-text: #1a1a2e;
  --color-muted: #555;
  --color-accent: #2563eb;
  --color-accent-light: #dbeafe;
  --color-border: #e5e7eb;
  --color-section-alt: #f8fafc;
  --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
  --font-serif: 'Lora', Georgia, serif;
  --max-width: 960px;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  font-size: 16px;
}

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

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

/* ===== Navigation ===== */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1.5rem;
}

.nav-brand {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
  text-decoration: none;
}

.nav-brand:hover { text-decoration: none; color: var(--color-accent); }

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

.nav-links a {
  color: var(--color-muted);
  font-size: 0.9rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  transition: color 0.2s;
}

.nav-links a:hover, .nav-links a.active {
  color: var(--color-accent);
  text-decoration: none;
}

/* ===== Hero (Home) ===== */
.hero {
  background: linear-gradient(135deg, #1e3a5f 0%, #2563eb 100%);
  color: #fff;
  padding: 5rem 1.5rem 4rem;
  text-align: center;
}

.hero h1 {
  font-family: var(--font-serif);
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 0.25rem;
}

.hero .subtitle {
  font-size: 1rem;
  opacity: 0.85;
  margin-bottom: 0.75rem;
}

.hero .tagline {
  font-size: 1.15rem;
  font-weight: 300;
  opacity: 0.95;
  letter-spacing: 0.04em;
}

/* ===== Content Sections ===== */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

section {
  padding: 3.5rem 0;
}

section:nth-child(even) {
  background: var(--color-section-alt);
}

section h2 {
  font-family: var(--font-serif);
  font-size: 1.6rem;
  margin-bottom: 1.5rem;
  position: relative;
  padding-bottom: 0.5rem;
}

section h2::after {
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 40px;
  height: 3px;
  background: var(--color-accent);
  border-radius: 2px;
}

.text-center h2::after { left: 50%; transform: translateX(-50%); }

/* ===== Research Cards ===== */
.research-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.25rem;
}

.research-card {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 1.5rem;
  transition: box-shadow 0.2s;
}

.research-card:hover {
  box-shadow: 0 4px 12px rgba(0,0,0,0.08);
}

.research-card h3 {
  font-size: 1.05rem;
  margin-bottom: 0.5rem;
  color: var(--color-accent);
}

.research-card p {
  font-size: 0.92rem;
  color: var(--color-muted);
  line-height: 1.65;
}

/* ===== People Page ===== */
.page-header {
  background: linear-gradient(135deg, #1e3a5f 0%, #2563eb 100%);
  color: #fff;
  padding: 3rem 1.5rem;
  text-align: center;
}

.page-header h1 {
  font-family: var(--font-serif);
  font-size: 2rem;
}

.pi-card {
  display: flex;
  gap: 2rem;
  align-items: flex-start;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: 10px;
  padding: 2rem;
  margin-bottom: 2rem;
}

.pi-card img {
  width: 180px;
  height: 220px;
  object-fit: cover;
  border-radius: 8px;
  flex-shrink: 0;
}

.pi-card h3 { font-size: 1.25rem; margin-bottom: 0.25rem; }
.pi-card .role { color: var(--color-muted); font-size: 0.9rem; margin-bottom: 0.15rem; }

.members-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1rem;
}

.member-card {
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: 8px;
  padding: 1.25rem;
  text-align: center;
}

.member-card .name { font-weight: 600; font-size: 0.95rem; }
.member-card .title { color: var(--color-muted); font-size: 0.85rem; }

.alumni-list {
  list-style: none;
  columns: 2;
  gap: 2rem;
}

.alumni-list li {
  padding: 0.35rem 0;
  font-size: 0.9rem;
  color: var(--color-muted);
  break-inside: avoid;
}

.alumni-list li strong { color: var(--color-text); }

/* ===== Team Photo ===== */
.team-photo {
  border-radius: 10px;
  margin: 1.5rem auto;
  max-width: 700px;
  box-shadow: 0 4px 16px rgba(0,0,0,0.1);
}

/* ===== Publications ===== */
.pub-year {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-accent);
  margin-top: 2rem;
  margin-bottom: 0.75rem;
  padding-bottom: 0.3rem;
  border-bottom: 2px solid var(--color-accent-light);
}

.pub-year:first-of-type { margin-top: 0; }

.pub-list { list-style: none; }

.pub-list li {
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.9rem;
  line-height: 1.6;
}

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

.pub-list .pub-title {
  font-weight: 600;
  color: var(--color-text);
}

.pub-list .pub-journal {
  font-style: italic;
  color: var(--color-muted);
}

.pub-list .pub-doi a {
  font-size: 0.82rem;
}

/* ===== Contact ===== */
.contact-bar {
  text-align: center;
  padding: 2rem 1.5rem;
  background: var(--color-section-alt);
}

.contact-bar a { font-weight: 600; }

/* ===== Footer ===== */
.site-footer {
  text-align: center;
  padding: 1.5rem;
  font-size: 0.8rem;
  color: var(--color-muted);
  border-top: 1px solid var(--color-border);
}

/* ===== Responsive ===== */
@media (max-width: 640px) {
  .hero h1 { font-size: 1.8rem; }
  .pi-card { flex-direction: column; align-items: center; text-align: center; }
  .pi-card img { width: 140px; height: 180px; }
  .alumni-list { columns: 1; }
  .nav-links { gap: 1rem; }
}