/* ---------------------------------------------------------
   Design tokens
--------------------------------------------------------- */
:root {
  --color-bg: #fdfdfb;
  --color-bg-alt: #f4f3ef;
  --color-surface: #ffffff;
  --color-text: #1c1c1a;
  --color-text-muted: #5b5a54;
  --color-border: #e4e2da;

  --color-accent: #24425f;
  --color-accent-strong: #172c42;
  --color-accent-tint: #e8edf2;

  --font-serif: "Source Serif 4", Georgia, "Times New Roman", serif;
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;

  --space-1: 0.5rem;
  --space-2: 1rem;
  --space-3: 1.5rem;
  --space-4: 2.25rem;
  --space-5: 3.5rem;
  --space-6: 5rem;

  --max-width: 1080px;
  --radius: 3px;
}

/* ---------------------------------------------------------
   Reset & base
--------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

h1, h2, h3, h4 {
  font-family: var(--font-serif);
  font-weight: 600;
  line-height: 1.2;
  margin: 0 0 var(--space-2);
  color: var(--color-accent-strong);
}

h1 { font-size: clamp(2.1rem, 4vw, 3rem); }
h2 { font-size: clamp(1.5rem, 3vw, 1.9rem); }
h3 { font-size: 1.2rem; }
h4 { font-size: 1rem; letter-spacing: 0.02em; text-transform: uppercase; color: var(--color-text-muted); }

p { margin: 0 0 var(--space-2); }

a {
  color: var(--color-accent);
  text-decoration-color: rgba(36, 66, 95, 0.35);
  text-underline-offset: 2px;
}
a:hover { text-decoration-color: currentColor; }

ul { margin: 0; padding: 0; }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-3);
}

.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

/* ---------------------------------------------------------
   Header / nav
--------------------------------------------------------- */
.site-header {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
  position: sticky;
  top: 0;
  z-index: 20;
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: var(--space-2);
  padding-bottom: var(--space-2);
}

.site-logo {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 1.1rem;
  color: var(--color-accent-strong);
  text-decoration: none;
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 0.4rem 0.6rem;
  cursor: pointer;
}

.nav-toggle span,
.nav-toggle span::before,
.nav-toggle span::after {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-accent-strong);
  position: relative;
  transition: transform 0.2s ease;
}
.nav-toggle span::before,
.nav-toggle span::after {
  content: "";
  position: absolute;
  left: 0;
}
.nav-toggle span::before { top: -6px; }
.nav-toggle span::after { top: 6px; }

.site-nav ul {
  display: flex;
  gap: var(--space-4);
  list-style: none;
}

.site-nav a {
  color: var(--color-text);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  padding: 0.25rem 0;
  border-bottom: 2px solid transparent;
}
.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: var(--color-accent-strong);
  border-bottom-color: var(--color-accent);
}

@media (max-width: 720px) {
  .nav-toggle { display: inline-flex; align-items: center; justify-content: center; }
  .site-nav {
    display: none;
    width: 100%;
    border-top: 1px solid var(--color-border);
  }
  .site-nav.is-open { display: block; }
  .site-nav ul {
    flex-direction: column;
    gap: 0;
    padding: var(--space-1) 0;
  }
  .site-nav a {
    display: block;
    padding: var(--space-1) 0;
  }
  .site-header .container {
    flex-wrap: wrap;
  }
}

/* ---------------------------------------------------------
   Buttons
--------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.7rem 1.4rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  border: 1px solid transparent;
  cursor: pointer;
}

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

.btn-secondary {
  background: transparent;
  color: var(--color-accent-strong);
  border-color: var(--color-border);
}
.btn-secondary:hover { border-color: var(--color-accent); }

/* ---------------------------------------------------------
   Hero
--------------------------------------------------------- */
.hero {
  position: relative;
  overflow: hidden;
  padding: var(--space-6) 0 var(--space-5);
}

.hero-decor {
  position: absolute;
  top: -10%;
  right: -6%;
  width: 480px;
  height: 480px;
  z-index: 0;
  pointer-events: none;
  color: var(--color-accent);
  opacity: 0.16;
  transform: rotate(180deg);
}

.hero .container {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: minmax(240px, 360px) 1fr;
  gap: var(--space-5);
  align-items: center;
}

.hero-photo-rect {
  width: 100%;
  aspect-ratio: 4 / 3;
  border-radius: 6px;
  background: var(--color-accent-tint);
  border: 1px solid var(--color-border);
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  overflow: hidden;
  flex-shrink: 0;
}
.hero-photo-rect img { width: 100%; height: 100%; object-fit: cover; }

.hero-title { margin-bottom: 0.3rem; }
.hero-role {
  font-family: var(--font-sans);
  font-weight: 600;
  color: var(--color-accent);
  font-size: 1.05rem;
  margin-bottom: var(--space-2);
}
.hero-pitch {
  font-size: 1.1rem;
  color: var(--color-text-muted);
  max-width: 60ch;
  margin-bottom: var(--space-3);
}
.hero-actions { display: flex; gap: var(--space-2); flex-wrap: wrap; }

@media (max-width: 720px) {
  .hero .container { grid-template-columns: 1fr; text-align: center; }
  .hero-actions { justify-content: center; }
  .hero-decor { width: 320px; height: 320px; }
}

/* ---------------------------------------------------------
   Research interests
--------------------------------------------------------- */
.interests-section { padding-top: var(--space-4); padding-bottom: var(--space-4); }
.interest-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  list-style: none;
  margin-top: var(--space-2);
}
.interest-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1.1rem;
  border: 1px solid var(--color-border);
  border-radius: 999px;
  background: var(--color-surface);
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--color-accent-strong);
}
.interest-chip::before {
  content: "";
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--color-accent);
  flex-shrink: 0;
}

/* ---------------------------------------------------------
   About / bio photo
--------------------------------------------------------- */
.about-section .container {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: var(--space-4);
  align-items: start;
}

.about-photo {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  background: var(--color-accent-tint);
  color: var(--color-accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-serif);
  font-size: 2.2rem;
  font-weight: 600;
  overflow: hidden;
  flex-shrink: 0;
}
.about-photo img { width: 100%; height: 100%; object-fit: cover; }

@media (max-width: 640px) {
  .about-section .container { grid-template-columns: 1fr; text-align: center; }
  .about-photo { margin: 0 auto; }
}

/* ---------------------------------------------------------
   Sections
--------------------------------------------------------- */
section.page-section {
  padding: var(--space-5) 0;
  border-top: 1px solid var(--color-border);
}

.about-content p { max-width: 68ch; color: var(--color-text-muted); }

.explore-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-3);
  margin-top: var(--space-3);
}

.explore-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-3);
  text-decoration: none;
  color: var(--color-text);
  display: block;
  transition: border-color 0.15s ease, transform 0.15s ease;
}
.explore-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
}
.explore-card h3 { margin-bottom: 0.35rem; color: var(--color-accent-strong); }
.explore-card p { color: var(--color-text-muted); margin: 0; font-size: 0.95rem; }

/* ---------------------------------------------------------
   Footer
--------------------------------------------------------- */
.site-footer {
  border-top: 1px solid var(--color-border);
  padding: var(--space-4) 0;
  background: var(--color-bg-alt);
}
.site-footer .container {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-2);
  font-size: 0.9rem;
  color: var(--color-text-muted);
}
.footer-links {
  display: flex;
  gap: var(--space-3);
  list-style: none;
}
.footer-links a { color: var(--color-text-muted); }
.footer-links a:hover { color: var(--color-accent-strong); }

/* ---------------------------------------------------------
   Research page
--------------------------------------------------------- */
.research-year-group {
  padding-top: var(--space-4);
  margin-top: var(--space-4);
  border-top: 1px solid var(--color-border);
}
.research-year-group:first-of-type {
  margin-top: 0;
  padding-top: 0;
  border-top: none;
}

.research-year {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--color-accent);
  margin-bottom: var(--space-3);
}

.research-entry {
  padding: var(--space-3) 0;
  border-top: 1px solid var(--color-border);
}
.research-entry:first-child { border-top: none; padding-top: 0; }

.research-title {
  max-width: 62ch;
  margin-bottom: 0.4rem;
}

.research-authors {
  color: var(--color-text-muted);
  font-size: 0.92rem;
  margin-bottom: 0.2rem;
}

.research-venue {
  color: var(--color-text-muted);
  font-size: 0.85rem;
  font-style: italic;
  margin-bottom: var(--space-2);
}

.research-abstract {
  margin-top: var(--space-2);
  max-width: 68ch;
}
.research-abstract summary {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  cursor: pointer;
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--color-accent-strong);
  list-style: none;
}
.research-abstract summary::-webkit-details-marker { display: none; }
.research-abstract summary::before {
  content: "▸";
  color: var(--color-accent);
  transition: transform 0.15s ease;
  font-size: 0.75rem;
}
.research-abstract[open] summary::before { transform: rotate(90deg); }
.research-abstract p {
  margin: var(--space-2) 0 0;
  padding-left: var(--space-2);
  border-left: 2px solid var(--color-accent-tint);
  color: var(--color-text-muted);
  font-size: 0.95rem;
  line-height: 1.65;
}

.contact-list {
  list-style: none;
  max-width: 420px;
  margin-top: var(--space-3);
}
.contact-list li { margin-bottom: var(--space-2); }
.contact-list a {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-surface);
  color: var(--color-text);
  text-decoration: none;
  font-weight: 600;
}
.contact-list a:hover { border-color: var(--color-accent); color: var(--color-accent-strong); }

.coming-soon {
  min-height: 50vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
}