:root {
  --bg-color: #fdfcfb;
  --text-primary: #1a1a1a;
  --text-secondary: #4a4a4a;
  --text-muted: #717171;
  --accent-color: #2a2a2a;
  --link-hover: #b86443;
  --border-color: #e5e5e5;
  --card-bg: #ffffff;
  --font-serif: "Fraunces", Georgia, serif;
  --font-sans: "Work Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --max-width: 1100px;
  --section-spacing: 6rem;
}

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

html {
  scroll-behavior: smooth;
}

body {
  background-color: var(--bg-color);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--link-hover);
}

ul {
  list-style: none;
}

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

/* Layout */
.page-container {
  width: 90%;
  max-width: var(--max-width);
  margin: 0 auto;
}

/* Header */
.site-header {
  padding: 2rem 0;
  border-bottom: 1px solid var(--border-color);
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 700;
}

.logo span {
  font-weight: 400;
  font-size: 1.1rem;
  color: var(--text-muted);
}

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

.main-nav a {
  font-size: 0.9rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
}

/* Hero Section */
.hero-section {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 4rem;
  align-items: center;
  padding: var(--section-spacing) 0;
}

.hero-content h1 {
  font-family: var(--font-serif);
  font-size: clamp(3rem, 6vw, 4.5rem);
  line-height: 1.1;
  margin-bottom: 1.5rem;
  font-weight: 700;
}

.subtitle {
  font-size: 1.4rem;
  color: var(--text-secondary);
  font-weight: 500;
  margin-bottom: 2rem;
  line-height: 1.4;
}

.hero-description {
  max-width: 35rem;
  margin-bottom: 2.5rem;
  font-size: 1.1rem;
  color: var(--text-secondary);
}

.hero-cta {
  display: flex;
  gap: 1.5rem;
}

.hero-image .portrait {
  width: 100%;
  border-radius: 4px;
  box-shadow: 20px 20px 0px rgba(0,0,0,0.05);
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 1rem 2rem;
  border-radius: 4px;
  font-weight: 600;
  font-size: 0.95rem;
  transition: all 0.2s ease;
  cursor: pointer;
}

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

.btn-primary:hover {
  background-color: #444;
  color: white;
  transform: translateY(-2px);
}

.btn-secondary {
  border: 1px solid var(--border-color);
  background: transparent;
  color: var(--text-primary);
}

.btn-secondary:hover {
  border-color: var(--accent-color);
  transform: translateY(-2px);
}

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

.section-title {
  font-family: var(--font-serif);
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--text-muted);
  margin-bottom: 3rem;
  font-weight: 600;
}

/* About Section */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 4rem;
}

.about-text p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  max-width: 40rem;
}

.about-highlights {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.highlight-item .label {
  display: block;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.highlight-item .value {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.5;
}

/* Work Section */
.work-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 2.5rem;
}

.work-card h3 {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  margin-bottom: 1rem;
}

.work-card p {
  color: var(--text-secondary);
  font-size: 1rem;
}

/* Research Section */
.research-layout {
  display: grid;
  grid-template-columns: 1fr 1.5fr;
  gap: 5rem;
}

.institutional-timeline h3, .publications-list h3 {
  font-family: var(--font-serif);
  font-size: 1.75rem;
  margin-bottom: 2rem;
}

.timeline-list li {
  margin-bottom: 2.5rem;
  position: relative;
  padding-left: 1.5rem;
}

.timeline-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.5rem;
  width: 6px;
  height: 6px;
  background: var(--accent-color);
  border-radius: 50%;
}

.timeline-list .time {
  display: block;
  font-size: 0.85rem;
  color: var(--text-muted);
  font-weight: 600;
}

.timeline-list .institution {
  display: block;
  font-size: 1.1rem;
  font-weight: 600;
  margin: 0.2rem 0;
}

.timeline-list .role {
  font-size: 0.95rem;
  color: var(--text-secondary);
}

.publications-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 2rem;
}

.pubmed-link {
  font-size: 0.85rem;
  font-weight: 600;
  text-decoration: underline;
}

.pub-list {
  padding-left: 1.2rem;
}

.pub-list li {
  margin-bottom: 1.5rem;
}

.pub-list li a {
  display: block;
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
  line-height: 1.4;
}

.pub-meta {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Now Section */
.now-content {
  max-width: 40rem;
}

.now-content p {
  font-size: 1.15rem;
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
}

/* Connect Section */
.connect-content {
  max-width: 40rem;
}

.connect-content p {
  font-size: 1.5rem;
  font-family: var(--font-serif);
  margin-bottom: 2.5rem;
}

/* Footer */
.site-footer {
  padding: 4rem 0;
  border-top: 1px solid var(--border-color);
  font-size: 0.9rem;
  color: var(--text-muted);
}

.footer-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-links {
  display: flex;
  gap: 2rem;
}

.coffee-link {
  font-weight: 600;
}

.scroll-top-button {
  position: fixed;
  right: 1.5rem;
  bottom: 1.5rem;
  z-index: 20;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 3rem;
  height: 3rem;
  padding: 0;
  border: 1px solid var(--border-color);
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.94);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 1.15rem;
  font-weight: 600;
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.08);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition:
    opacity 0.2s ease,
    visibility 0.2s ease,
    transform 0.2s ease,
    border-color 0.2s ease,
    color 0.2s ease;
}

.scroll-top-icon {
  line-height: 1;
}

.scroll-top-label {
  position: absolute;
  right: calc(100% + 0.75rem);
  top: 50%;
  padding: 0.45rem 0.7rem;
  border: 1px solid var(--border-color);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.96);
  color: var(--text-primary);
  font-size: 0.8rem;
  font-weight: 600;
  white-space: nowrap;
  opacity: 0;
  visibility: hidden;
  transform: translateY(-50%) translateX(6px);
  transition:
    opacity 0.2s ease,
    visibility 0.2s ease,
    transform 0.2s ease;
  pointer-events: none;
}

.scroll-top-button:hover {
  border-color: var(--accent-color);
  color: var(--link-hover);
}

.scroll-top-button:hover .scroll-top-label,
.scroll-top-button:focus-visible .scroll-top-label {
  opacity: 1;
  visibility: visible;
  transform: translateY(-50%) translateX(0);
}

.scroll-top-button:focus-visible {
  outline: 2px solid var(--link-hover);
  outline-offset: 3px;
}

.scroll-top-button.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

/* Responsive */
@media (max-width: 900px) {
  .hero-section {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 3rem;
  }

  .hero-image {
    order: -1;
  }
  
  .hero-content h1 {
    font-size: 3.5rem;
  }
  
  .hero-description {
    margin-left: auto;
    margin-right: auto;
  }
  
  .hero-cta {
    justify-content: center;
  }
  
  .hero-image {
    max-width: 400px;
    margin: 0 auto;
  }

  .scroll-top-button {
    right: 1rem;
    bottom: 1rem;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 3rem;
  }

  .research-layout {
    grid-template-columns: 1fr;
    gap: 4rem;
  }
}

@media (max-width: 600px) {
  .header-inner {
    flex-direction: column;
    gap: 1rem;
  }

  .main-nav {
    gap: 0.85rem;
    flex-wrap: wrap;
    justify-content: center;
  }

  .site-header {
    padding: 1.4rem 0 1rem;
  }

  .hero-section {
    padding: 2.25rem 0 4rem;
    gap: 1.5rem;
  }

  .hero-image {
    margin-top: 0;
  }

  .hero-content h1 {
    font-size: 2.5rem;
  }

  .hero-cta {
    flex-direction: column;
    gap: 1rem;
  }

  .footer-container {
    flex-direction: column;
    gap: 2rem;
    text-align: center;
  }
}