:root {
  --bg: #FFFFFF;
  --surface: #F7F6F4;
  --text-primary: #1B1B1B;
  --text-secondary: #545454;
  --text-tertiary: #8A8A8A;
  --accent: #2E2E2E;
  --accent-hover: #000000;
  --border: #E2E2E2;
  --font-heading: 'Fira Sans', Arial, sans-serif;
  --font-body: 'Fira Sans', Arial, sans-serif;
  --max-width: 900px;
  --nav-height: 60px;
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

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

body {
  font-family: var(--font-body);
  font-size: .95rem;
  line-height: 1.7;
  color: var(--text-primary);
  background-color: var(--bg);
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 3px;
  transition: color 0.2s ease;
}
a:hover { color: var(--accent-hover); }

p { margin-bottom: 1rem; }
p:last-child { margin-bottom: 0; }

h1, h2, h3 {
  font-family: var(--font-heading);
  line-height: 1.2;
  color: var(--text-primary);
}

/* Navigation */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--bg);
  border-bottom: 1px solid var(--border);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: flex-end;
  height: var(--nav-height);
}

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

.nav-links a {
  color: var(--text-primary);
  font-size: 0.875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.5rem 0;
  border-bottom: 2px solid transparent;
  text-decoration: none;
  transition: color 0.2s, border-color 0.2s;
}
.nav-links a:hover { color: var(--accent); }
.nav-links a.active { color: var(--accent); border-bottom-color: var(--accent); }

/* Home page */
.home-content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: .5rem 1.5rem 2rem;
}

.home-intro {
  display: flex;
  align-items: flex-start;
  gap: 2.2rem;
  text-align: left;
}

.home-photo {
  width: 160px;
  height: 160px;
  object-fit: cover;
  object-position: center 30%;
  display: block;
  flex-shrink: 0;
  border-radius: 50%;
  box-shadow: 0 12px 24px rgba(0,0,0,0.10);
}

.home-text-col { flex: 1; min-width: 0; }

.home-intro h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: .4rem;
  text-align: left;
}

.home-subtitle {
  font-size: .95rem;
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
}

.home-bio {
  max-width: 760px;
  text-align: left;
}

.home-bio p {
  font-size: 0.9rem;
  line-height: 1.6;
  margin-bottom: 0.9rem;
}

.home-links {
  margin-top: 1.6rem;
  font-size: .875rem;
  color: var(--text-secondary);
}
.home-links a { margin: 0 .4rem; }

@media (max-width: 600px) {
  .home-content { padding-top: 2.5rem; }
  .home-intro { flex-direction: column; align-items: center; text-align: center; }
  .home-photo { width: 140px; height: 140px; }
  .home-intro h1 { font-size: 1.8rem; letter-spacing: 0.04em; text-align: center; }
  .home-subtitle { text-align: center; }
  .home-bio { text-align: left; }
}

/* Inner page layout */
.page-content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 4rem 1.5rem 5rem;
}

.section-heading {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--accent);
}

.section-heading:not(:first-child) { margin-top: 3rem; }

.papers-list { margin-bottom: 1rem; }

.paper {
  display: flex;
  gap: 1rem;
  padding-bottom: 1.6rem;
  margin-bottom: 1.6rem;
  border-bottom: 1px solid var(--border);
}
.paper:last-child { border-bottom: none; padding-bottom: 0; margin-bottom: 0; }

.paper-num {
  font-size: 0.875rem;
  color: var(--text-tertiary);
  flex-shrink: 0;
  width: 3.5em;
  padding-top: 0.1em;
  font-family: var(--font-heading);
}

.paper-body { flex: 1; }

.paper-title {
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
  color: var(--text-primary);
}

.paper-venue, .paper-coauthors {
  font-size: .9rem;
  color: var(--text-secondary);
  margin-bottom: 0.1rem;
}

.paper-actions { position: relative; margin-top: 0.35rem; }

.paper-abstract { margin: 0; }

.paper-abstract summary {
  display: inline-block;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent);
  cursor: pointer;
  user-select: none;
  list-style: none;
}
.paper-abstract summary::-webkit-details-marker { display: none; }

.paper-action {
  display: inline-block;
  margin-left: 1.25rem;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent);
  text-decoration: none;
}
.paper-abstract summary:hover, .paper-action:hover { color: var(--accent-hover); }

.paper-abstract-text { margin-top: 0.75rem; }
.paper-abstract-text p { font-size: 0.85rem; color: var(--text-secondary); line-height: 1.7; }

/* Footer */
.site-footer {
  background-color: var(--surface);
  border-top: 1px solid var(--border);
  padding: 1.5rem 0;
  text-align: center;
}
.site-footer p { font-size: 0.875rem; color: var(--text-tertiary); margin: 0; }

@media (max-width: 600px) {
  .nav-container { height: auto; padding-top: 0.75rem; padding-bottom: 0.75rem; justify-content: center; flex-wrap: wrap; gap: 0.4rem; }
  .nav-links { gap: 1rem; }
  .page-content { padding-top: 2.5rem; }
  .paper { flex-direction: column; gap: .2rem; }
  .paper-num { width: auto; }
}