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

:root {
  --accent: #1a5490;
  --accent-hover: #0d3e6f;
  --accent-light: #f0f6fc;
  --accent-soft: #e8f0f9;
  --text: #0f1419;
  --text-muted: #57606a;
  --text-subtle: #8b949e;
  --border: #d0d7de;
  --border-light: #e8ecf0;
  --bg: #ffffff;
  --bg-subtle: #f6f8fa;
  --bg-card: #fafbfc;
  --bg-code: #f6f8fa;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04), 0 1px 2px rgba(0, 0, 0, 0.03);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.05), 0 2px 4px rgba(0, 0, 0, 0.03);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.08), 0 2px 6px rgba(0, 0, 0, 0.04);
  --max-width: 820px;
  --font: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}

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

body {
  font-family: var(--font);
  color: var(--text);
  background: var(--bg-subtle);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s ease;
}
a:hover {
  color: var(--accent-hover);
  text-decoration: none;
}

/* === Layout === */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem 4rem;
  background: var(--bg);
  min-height: calc(100vh - 200px);
}

/* === Header & Nav === */
header {
  text-align: center;
  padding: 3.5rem 2rem 0;
  max-width: var(--max-width);
  margin: 0 auto;
  background: var(--bg);
  border-bottom: 1px solid var(--border-light);
}

header h1 {
  font-size: 1.65rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  margin-bottom: 1.5rem;
  color: var(--text);
}

nav {
  display: flex;
  justify-content: center;
  gap: 2.5rem;
  padding-bottom: 1.75rem;
}

nav a {
  color: var(--text-muted);
  font-size: 0.875rem;
  font-weight: 500;
  letter-spacing: 0.01em;
  text-decoration: none;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid transparent;
  transition: all 0.2s ease;
  position: relative;
}

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

nav a.active {
  color: var(--text);
  border-bottom-color: var(--text);
}

/* === Home page === */
.home-grid {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 2.5rem;
  align-items: start;
  padding: 3rem 0;
}

.home-grid img {
  width: 100%;
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-light);
}

.home-info h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 1rem;
  color: var(--text);
  letter-spacing: -0.01em;
}

.home-info p {
  margin-bottom: 1rem;
  font-size: 0.9375rem;
  color: var(--text);
  line-height: 1.7;
}

.home-info .contact {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.8;
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border-light);
}

.home-links {
  display: flex;
  gap: 0.75rem;
  margin-top: 1.25rem;
}

.home-links a {
  display: inline-flex;
  align-items: center;
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.01em;
  padding: 0.5rem 1.125rem;
  border: 1.5px solid var(--border);
  color: var(--text);
  border-radius: 6px;
  text-decoration: none;
  transition: all 0.2s ease;
  box-shadow: var(--shadow-sm);
}

.home-links a:hover {
  background: var(--text);
  color: var(--bg);
  border-color: var(--text);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

/* === Section headings === */
.section-heading {
  font-size: 0.9375rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent);
  margin: 3rem 0 1.5rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--accent);
}

.section-heading:first-of-type {
  margin-top: 2rem;
}

.sub-heading {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-subtle);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin: 2.25rem 0 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border-light);
}

/* === Paper cards === */
.paper {
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--border-light);
  transition: all 0.2s ease;
}

.paper:last-child {
  border-bottom: none;
}

.paper:hover {
  padding-left: 0.5rem;
  margin-left: -0.5rem;
}

.paper-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1.25rem;
}

.paper-title {
  font-size: 0.9375rem;
  font-weight: 600;
  line-height: 1.5;
  letter-spacing: -0.01em;
}

.paper-title a {
  color: var(--text);
  transition: color 0.2s ease;
}

.paper-title a:hover {
  color: var(--accent);
}

.paper-year {
  font-size: 0.8125rem;
  color: var(--text-subtle);
  font-weight: 500;
  white-space: nowrap;
  flex-shrink: 0;
  padding-top: 2px;
}

.paper-authors {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
  line-height: 1.5;
}

.paper-venue {
  font-size: 0.875rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 0.25rem;
  line-height: 1.5;
}

.paper-status {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 0.25rem 0.625rem;
  border-radius: 4px;
  margin-top: 0.375rem;
  border: 1px solid var(--accent-light);
}

.paper-awards {
  font-size: 0.8125rem;
  color: #b8860b;
  margin-top: 0.375rem;
  font-weight: 500;
}

.paper-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.75rem;
  align-items: center;
}

.paper-links a,
.paper-links button {
  display: inline-flex;
  align-items: center;
  font-family: var(--font);
  font-size: 0.75rem;
  font-weight: 500;
  padding: 0.375rem 0.75rem;
  border-radius: 5px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text-muted);
  cursor: pointer;
  text-decoration: none;
  transition: all 0.2s ease;
  line-height: 1.4;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.02);
}

.paper-links a:hover,
.paper-links button:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-light);
  text-decoration: none;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
  transform: translateY(-1px);
}

/* Special styling for Data and Project website links */
.paper-links a.data-link {
  background: #f0fdf4;
  border-color: #86efac;
  color: #166534;
}

.paper-links a.data-link:hover {
  background: #dcfce7;
  border-color: #4ade80;
  color: #15803d;
  box-shadow: 0 2px 4px rgba(74, 222, 128, 0.15);
}

.paper-links .sep {
  width: 1px;
  height: 18px;
  background: var(--border-light);
  margin: 0 0.25rem;
}

/* Abstract & BibTeX panels */
.paper-abstract,
.paper-bibtex {
  display: none;
  margin-top: 0.875rem;
  padding: 1rem 1.25rem;
  border-radius: 6px;
  font-size: 0.875rem;
  line-height: 1.7;
  animation: slideDown 0.2s ease-out;
}

.paper-abstract.open,
.paper-bibtex.open {
  display: block;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.paper-abstract {
  background: var(--accent-light);
  color: var(--text);
  border-left: 3px solid var(--accent);
  box-shadow: var(--shadow-sm);
}

.paper-bibtex {
  background: var(--bg-code);
  border: 1px solid var(--border-light);
  position: relative;
  box-shadow: var(--shadow-sm);
}

.paper-bibtex pre {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-all;
  margin: 0;
  color: var(--text);
}

.paper-bibtex .copy-btn {
  position: absolute;
  top: 0.75rem;
  right: 0.75rem;
  font-family: var(--font);
  font-size: 0.6875rem;
  font-weight: 500;
  padding: 0.375rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: 5px;
  background: var(--bg);
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.2s ease;
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
}

.paper-bibtex .copy-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-light);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.08);
}

/* Media coverage toggle */
.paper-media {
  display: none;
  margin-top: 0.4rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  line-height: 1.6;
}

.paper-media.open {
  display: block;
  animation: slideDown 0.15s ease-out;
}

/* === Work in progress (minimal) === */
.wip-item {
  padding: 0.875rem 0;
  font-size: 0.9375rem;
  border-bottom: 1px solid var(--border-light);
}

.wip-item:last-child {
  border-bottom: none;
}

.wip-item .paper-title {
  font-weight: 600;
  color: var(--text);
}

.wip-item .paper-authors {
  display: inline;
  color: var(--text-muted);
  font-size: 0.875rem;
}

/* === Teaching page === */
.course {
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--border-light);
  transition: all 0.2s ease;
}

.course:last-child {
  border-bottom: none;
}

.course:hover {
  padding-left: 0.5rem;
  margin-left: -0.5rem;
}

.course-title {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--text);
  letter-spacing: -0.01em;
}

.course-meta {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
  line-height: 1.5;
}

.course-links {
  margin-top: 0.5rem;
}

.course-links a {
  font-size: 0.8125rem;
  color: var(--accent);
  transition: color 0.2s ease;
}

.course-links a:hover {
  color: var(--accent-hover);
}

/* === Data page === */
.data-project {
  padding: 1.75rem 0;
  border-bottom: 1px solid var(--border-light);
  transition: all 0.2s ease;
}

.data-project:last-child {
  border-bottom: none;
}

.data-project:hover {
  padding-left: 0.5rem;
  margin-left: -0.5rem;
}

.data-project h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 0.5rem;
  letter-spacing: -0.01em;
}

.data-project p {
  font-size: 0.9375rem;
  color: var(--text);
  margin-bottom: 0.75rem;
  line-height: 1.7;
}

.data-project ul {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin: 0.5rem 0 0.75rem 1.5rem;
  line-height: 1.8;
}

.data-project ul li {
  margin-bottom: 0.25rem;
}

.data-project .paper-links {
  margin-top: 0.75rem;
}

/* === Footer === */
footer {
  text-align: center;
  padding: 2rem;
  font-size: 0.8125rem;
  color: var(--text-subtle);
  background: var(--bg);
  border-top: 1px solid var(--border-light);
  max-width: var(--max-width);
  margin: 3rem auto 0;
}

/* === Responsive === */
@media (max-width: 768px) {
  .container {
    padding: 0 1.5rem 3rem;
  }

  header {
    padding: 2.5rem 1.5rem 0;
  }

  .home-grid {
    grid-template-columns: 1fr;
    text-align: center;
    gap: 2rem;
    padding: 2rem 0;
  }

  .home-grid img {
    max-width: 200px;
    margin: 0 auto;
  }

  .home-info .contact {
    border-top: none;
    padding-top: 0;
    margin-top: 1.25rem;
  }

  nav {
    gap: 1.75rem;
    flex-wrap: wrap;
  }

  .paper-header {
    flex-direction: column;
    gap: 0.25rem;
  }

  .paper-year {
    order: -1;
    padding-top: 0;
    font-size: 0.75rem;
  }

  .paper:hover {
    padding-left: 0;
    margin-left: 0;
  }

  .course:hover,
  .data-project:hover {
    padding-left: 0;
    margin-left: 0;
  }

  .home-links {
    justify-content: center;
    flex-wrap: wrap;
  }

  .section-heading {
    font-size: 0.875rem;
    margin: 2.5rem 0 1.25rem;
  }

  .section-heading:first-of-type {
    margin-top: 1.5rem;
  }
}

/* === Impact Statement === */
.impact-statement {
  font-size: 0.9375rem;
  color: var(--text-muted);
  margin-top: 1.5rem;
}

/* === Back to Top Button === */
#backToTop {
  display: none;
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  z-index: 99;
  border: none;
  outline: none;
  background-color: var(--accent);
  color: white;
  cursor: pointer;
  padding: 0.875rem 1.25rem;
  border-radius: 8px;
  font-size: 0.875rem;
  font-weight: 600;
  font-family: var(--font);
  box-shadow: var(--shadow-lg);
  transition: all 0.3s ease;
  letter-spacing: 0.02em;
}

#backToTop:hover {
  background-color: var(--accent-hover);
  transform: translateY(-3px);
  box-shadow: 0 12px 28px rgba(0, 0, 0, 0.12), 0 4px 8px rgba(0, 0, 0, 0.06);
}

#backToTop:active {
  transform: translateY(-1px);
}

@media (max-width: 768px) {
  #backToTop {
    bottom: 1.5rem;
    right: 1.5rem;
    padding: 0.75rem 1rem;
    font-size: 0.8125rem;
  }
}