/* ── CSS Custom Properties ───────────────────────────────────── */
:root {
  --bg-page:          #efefef;
  --bg-card:          #ffffff;
  --bg-header:        #1f1f1f;
  --border-card:      #e0e0e0;
  --border-divider:   #eee;
  --border-subtle:    #f0f0f0;
  --border-col:       #e8e8e8;
  --text-h:           #111;
  --text-body:        #333;
  --text-secondary:   #444;
  --text-muted:       #555;
  --text-faint:       #888;
  --text-faintest:    #999;
  --text-footer:      #aaa;
  --link:             #0077aa;
  --link-hover:       #005588;
  --tag-bg:           #f0f4f8;
  --tag-border:       #dce3ea;
  --tag-color:        #445;
  --shadow-card:      0 1px 4px rgba(0,0,0,.06);
  --orcid-bg:         #f0faf5;
  --orcid-border:     #a7f3d0;
  --orcid-color:      #059669;
  --arxiv-bg:         #fff8f0;
  --arxiv-border:     #f6d093;
  --arxiv-color:      #b45309;
  --sk-a:             #f0f0f0;
  --sk-b:             #e0e0e0;
}

/* Dark theme variables — shared by system preference and manual toggle */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg-page:          #111;
    --bg-card:          #1a1a1a;
    --border-card:      #2a2a2a;
    --border-divider:   #252525;
    --border-subtle:    #202020;
    --border-col:       #2a2a2a;
    --text-h:           #e8e8e8;
    --text-body:        #bbb;
    --text-secondary:   #999;
    --text-muted:       #777;
    --text-faint:       #555;
    --text-faintest:    #444;
    --text-footer:      #444;
    --link:             #4db8e8;
    --link-hover:       #80d0f5;
    --tag-bg:           #1e2530;
    --tag-border:       #2d3a48;
    --tag-color:        #8aabb8;
    --shadow-card:      0 1px 4px rgba(0,0,0,.5);
    --orcid-bg:         #0a2018;
    --orcid-border:     #1a4a30;
    --orcid-color:      #34d399;
    --arxiv-bg:         #201408;
    --arxiv-border:     #4a2e08;
    --arxiv-color:      #fbbf24;
    --sk-a:             #252525;
    --sk-b:             #2e2e2e;
  }
}

/* Manual dark override (set by toggle button, saved to localStorage) */
:root[data-theme="dark"] {
  --bg-page:          #111;
  --bg-card:          #1a1a1a;
  --border-card:      #2a2a2a;
  --border-divider:   #252525;
  --border-subtle:    #202020;
  --border-col:       #2a2a2a;
  --text-h:           #e8e8e8;
  --text-body:        #bbb;
  --text-secondary:   #999;
  --text-muted:       #777;
  --text-faint:       #555;
  --text-faintest:    #444;
  --text-footer:      #444;
  --link:             #4db8e8;
  --link-hover:       #80d0f5;
  --tag-bg:           #1e2530;
  --tag-border:       #2d3a48;
  --tag-color:        #8aabb8;
  --shadow-card:      0 1px 4px rgba(0,0,0,.5);
  --orcid-bg:         #0a2018;
  --orcid-border:     #1a4a30;
  --orcid-color:      #34d399;
  --arxiv-bg:         #201408;
  --arxiv-border:     #4a2e08;
  --arxiv-color:      #fbbf24;
  --sk-a:             #252525;
  --sk-b:             #2e2e2e;
}

/* ── Reset ───────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
img  { display: block; max-width: 100%; }
a    { color: inherit; text-decoration: none; }

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  font-size: 15px;
  line-height: 1.65;
  color: var(--text-body);
  background: var(--bg-page);
  -webkit-font-smoothing: antialiased;
  transition: background-color 0.25s ease, color 0.25s ease;
}

.card {
  transition: background-color 0.25s ease, border-color 0.25s ease;
}

/* ── Header ──────────────────────────────────────────────────── */
#site-header {
  position: sticky;
  top: 0; z-index: 100;
  background: var(--bg-header);
  height: 52px;
  display: flex;
  align-items: center;
}

.header-inner {
  width: 100%; max-width: 980px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: relative;
}

.site-title {
  font-size: 1rem; font-weight: 600;
  color: #fff; letter-spacing: .01em;
  white-space: nowrap;
}

/* Theme toggle button */
.theme-toggle {
  background: none; border: none; cursor: pointer;
  color: rgba(255,255,255,.65);
  font-size: 0.95rem;
  padding: 0.4rem 0.5rem;
  border-radius: 4px;
  line-height: 1;
  transition: color 0.15s;
  flex-shrink: 0;
}
.theme-toggle:hover { color: #fff; }

/* Hamburger button */
.nav-toggle {
  display: none;
  background: none; border: none; cursor: pointer;
  padding: 0.4rem;
  flex-direction: column;
  align-items: center;
  gap: 5px;
}

.nav-toggle span {
  display: block; width: 22px; height: 2px;
  background: rgba(255,255,255,.8);
  border-radius: 2px;
  transition: transform 0.22s ease, opacity 0.22s ease;
}

.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

nav ul {
  list-style: none;
  display: flex; gap: 0;
}

nav ul li a {
  display: block;
  font-size: 0.85rem; font-weight: 400;
  color: rgba(255,255,255,.7);
  padding: 0.35rem 0.9rem;
  border-radius: 4px;
  transition: color 0.15s, background 0.15s;
}

nav ul li a:hover { color: #fff; }

nav ul li a.active {
  color: #fff; font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ── Layout ──────────────────────────────────────────────────── */
main {
  max-width: 980px;
  margin: 1.75rem auto;
  padding: 0 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

/* ── Card ────────────────────────────────────────────────────── */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: 8px;
  padding: 2rem 2.25rem;
  box-shadow: var(--shadow-card);
}

/* ── Profile ─────────────────────────────────────────────────── */
.profile-body {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 2.5rem;
}

.profile-text { flex: 1; }

.profile-text h1 {
  font-size: 2.1rem; font-weight: 700;
  color: var(--text-h);
  letter-spacing: -0.02em; line-height: 1.15;
  margin-bottom: 0.3rem;
}

.profile-title { font-size: 0.95rem; color: var(--text-muted); margin-bottom: 0.25rem; }

.profile-affil {
  display: flex; align-items: center; gap: 0.45rem;
  font-size: 0.9rem; color: var(--text-body);
  margin-bottom: 1.1rem;
}

.affil-dot { width: 16px; height: 16px; border-radius: 50%; flex-shrink: 0; }

.profile-text p { font-size: 0.92rem; color: var(--text-secondary); margin-bottom: 0.85rem; max-width: 640px; }

.social-links {
  margin-top: 1.5rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border-divider);
  display: flex; flex-wrap: wrap; gap: 0.25rem 1.5rem;
}

.social-links a {
  display: inline-flex; align-items: center; gap: 0.4rem;
  font-size: 0.85rem; color: var(--link);
  transition: color 0.15s;
}
.social-links a:hover { color: var(--link-hover); text-decoration: underline; }
.social-links a i { font-size: 0.9rem; }

.profile-photo-wrap { flex-shrink: 0; width: 160px; }

.profile-photo-wrap img {
  width: 160px; height: 200px;
  object-fit: cover;
  border: 1px solid var(--border-card);
  border-radius: 4px;
}

/* ── Two-column card (Education + Awards) ────────────────────── */
.two-col-card { display: flex; gap: 0; align-items: flex-start; padding: 1.75rem 0; }
.two-col-left, .two-col-right { flex: 1; padding: 0 2.25rem; }
.col-divider { width: 1px; align-self: stretch; background: var(--border-col); flex-shrink: 0; }

.two-col-card h2 {
  font-size: 0.95rem; font-weight: 600; color: var(--text-h);
  margin-bottom: 1.25rem;
  display: flex; align-items: center; gap: 0.5rem;
}
.two-col-card h2 i { color: var(--text-faint); font-size: 0.85rem; }

.edu-item { display: flex; align-items: flex-start; gap: 0.85rem; margin-bottom: 1.25rem; }
.edu-item:last-child { margin-bottom: 0; }

.edu-logo {
  width: 36px; height: 36px; border-radius: 50%;
  color: #fff; font-size: 0.6rem; font-weight: 700;
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0; letter-spacing: .02em;
}

.edu-details {
  flex: 1; display: flex; flex-direction: column;
  gap: 0.05rem; font-size: 0.85rem; color: var(--text-muted); line-height: 1.5;
}
.edu-details strong { font-size: 0.9rem; font-weight: 600; color: var(--text-h); }

.edu-date { font-size: 0.78rem; color: var(--text-faint); white-space: nowrap; padding-top: 0.15rem; font-style: italic; }

.awards-list { list-style: none; display: flex; flex-direction: column; gap: 0.65rem; }

.awards-list li {
  display: flex; align-items: baseline; justify-content: space-between; gap: 1rem;
  font-size: 0.88rem; color: var(--text-secondary);
  padding-bottom: 0.65rem;
  border-bottom: 1px dashed var(--border-divider);
}
.awards-list li:last-child { border-bottom: none; padding-bottom: 0; }

.award-name { flex: 1; }
.award-year { font-size: 0.82rem; color: var(--text-faint); white-space: nowrap; }

/* ── Section headings ────────────────────────────────────────── */
.section-heading {
  font-size: 0.95rem; font-weight: 600; color: var(--text-h);
  margin-bottom: 1.25rem;
  display: flex; align-items: center; gap: 0.5rem;
  padding-bottom: 0.75rem;
  border-bottom: 1px solid var(--border-divider);
}
.section-heading i { color: var(--text-faint); font-size: 0.85rem; }

/* ── News / Research / Talks list ────────────────────────────── */
.news-group { display: flex; gap: 1.5rem; margin-bottom: 0.75rem; }
.news-group:last-child { margin-bottom: 0; }
.news-year { font-size: 0.85rem; font-weight: 700; color: var(--text-body); width: 36px; flex-shrink: 0; padding-top: 0.15rem; }
.news-items { flex: 1; display: flex; flex-direction: column; gap: 0.6rem; }

.news-item {
  display: flex; align-items: flex-start; justify-content: space-between; gap: 1.5rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid var(--border-subtle);
  font-size: 0.88rem; color: var(--text-secondary);
}
.news-items .news-item:last-child { border-bottom: none; padding-bottom: 0; }

.news-content { flex: 1; line-height: 1.55; }
.news-content strong { color: var(--text-h); }
.news-meta { display: block; font-size: 0.8rem; color: var(--text-faint); margin-top: 0.2rem; font-style: italic; }
.news-date { font-size: 0.78rem; color: var(--text-faintest); white-space: nowrap; padding-top: 0.15rem; font-style: italic; }

/* Talk type badge */
.talk-type {
  display: inline-block; font-size: 0.68rem; font-weight: 700;
  text-transform: uppercase; letter-spacing: .06em;
  padding: 0.1rem 0.45rem; border-radius: 3px; margin-left: 0.4rem;
  vertical-align: middle;
}
.talk-type-presentation { background: #e0f0ff; color: #1a6ea8; }
.talk-type-poster       { background: #f0f0f0; color: #555; }

@media (prefers-color-scheme: dark) {
  html:not([data-theme="light"]) .talk-type-presentation { background: #1a3050; color: #70b8e8; }
  html:not([data-theme="light"]) .talk-type-poster       { background: #252525; color: #888; }
}
html[data-theme="dark"] .talk-type-presentation { background: #1a3050; color: #70b8e8; }
html[data-theme="dark"] .talk-type-poster       { background: #252525; color: #888; }

/* ── Skills ──────────────────────────────────────────────────── */
.skills-row { display: flex; flex-wrap: wrap; gap: 1.5rem 2.5rem; }
.skill-group { display: flex; flex-direction: column; gap: 0.5rem; }
.skill-label { font-size: 0.75rem; font-weight: 600; text-transform: uppercase; letter-spacing: .08em; color: var(--text-faint); }
.tag-list { display: flex; flex-wrap: wrap; gap: 0.35rem; }
.tag {
  font-size: 0.78rem; font-weight: 500;
  padding: 0.2rem 0.6rem; border-radius: 4px;
  background: var(--tag-bg); border: 1px solid var(--tag-border); color: var(--tag-color);
}

/* ── Teaching / Experience ───────────────────────────────────── */
.teaching-item {
  display: flex; align-items: baseline; justify-content: space-between; gap: 1rem;
  font-size: 0.88rem; color: var(--text-secondary);
  padding-bottom: 0.6rem; border-bottom: 1px solid var(--border-subtle);
}
.teaching-item:last-child { border-bottom: none; padding-bottom: 0; }
.teaching-role { font-weight: 600; color: var(--text-h); margin-right: 0.3rem; }
.teaching-course { color: var(--text-muted); }
.teaching-date { font-size: 0.78rem; color: var(--text-faintest); white-space: nowrap; font-style: italic; }

/* ── Muted ───────────────────────────────────────────────────── */
.muted { font-size: 0.88rem; color: var(--text-faintest); font-style: italic; }

/* ── Publications ────────────────────────────────────────────── */
.pub-card { display: flex; gap: 1.25rem; padding: 1.1rem 0; border-bottom: 1px solid var(--border-subtle); align-items: flex-start; }
.pub-card:last-child { border-bottom: none; padding-bottom: 0; }
.pub-thumb { width: 110px; height: 80px; object-fit: cover; border: 1px solid var(--border-card); border-radius: 4px; flex-shrink: 0; }
.pub-body { flex: 1; }
.pub-title { font-size: 0.95rem; font-weight: 600; color: var(--text-h); margin-bottom: 0.2rem; line-height: 1.4; }
.pub-authors { font-size: 0.82rem; color: var(--text-muted); margin-bottom: 0.2rem; }
.pub-venue { font-size: 0.82rem; color: var(--text-faint); margin-bottom: 0.4rem; display: flex; align-items: center; gap: 0.4rem; flex-wrap: wrap; }
.pub-abstract { font-size: 0.82rem; color: var(--text-muted); margin-bottom: 0.4rem; line-height: 1.5; }
.pub-links { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.pub-links a { font-size: 0.8rem; color: var(--link); }
.pub-links a:hover { text-decoration: underline; }

.pub-badge {
  display: inline-block; font-size: 0.7rem; font-weight: 700;
  padding: 0.15rem 0.55rem; border-radius: 99px;
  background: #0d9488; color: #fff; letter-spacing: .03em;
}

.pub-source-tag {
  display: inline-flex; align-items: center; gap: 0.25rem;
  font-size: 0.7rem; font-weight: 600;
  padding: 0.15rem 0.5rem; border-radius: 99px;
  background: var(--orcid-bg); border: 1px solid var(--orcid-border); color: var(--orcid-color);
}

.pub-source-arxiv {
  background: var(--arxiv-bg); border-color: var(--arxiv-border); color: var(--arxiv-color);
}

/* ── Contact ─────────────────────────────────────────────────── */
#contact > p { font-size: 0.9rem; color: var(--text-muted); margin-bottom: 1.25rem; }

.contact-grid { display: flex; flex-direction: column; gap: 0.5rem; }

.contact-row {
  display: flex; align-items: center; gap: 0.65rem;
  font-size: 0.88rem; color: var(--link);
  padding: 0.3rem 0; transition: color 0.15s;
}
.contact-row:hover { color: var(--link-hover); text-decoration: underline; }
.contact-row i { width: 16px; text-align: center; color: var(--text-faint); font-size: 0.85rem; }

/* ── Footer ──────────────────────────────────────────────────── */
footer { text-align: center; padding: 1.5rem; font-size: 0.8rem; color: var(--text-footer); }

/* ── Skeleton shimmer ────────────────────────────────────────── */
@keyframes shimmer {
  0%   { background-position: -600px 0; }
  100% { background-position:  600px 0; }
}

.sk {
  display: block; border-radius: 4px; margin-bottom: 0.45rem;
  background: linear-gradient(90deg, var(--sk-a) 25%, var(--sk-b) 50%, var(--sk-a) 75%);
  background-size: 1200px 100%;
  animation: shimmer 1.5s ease-in-out infinite;
}

.sk:last-child { margin-bottom: 0; }

/* ── Responsive / Mobile nav ─────────────────────────────────── */
@media (max-width: 700px) {
  /* Hamburger visible */
  .nav-toggle { display: flex; }

  /* Nav collapses below header */
  #site-header { position: sticky; }
  nav {
    display: none;
    position: absolute;
    top: 52px; left: 0; right: 0;
    background: var(--bg-header);
    border-top: 1px solid rgba(255,255,255,.08);
    padding: 0.5rem 0 1rem;
    z-index: 200;
  }
  nav.open { display: block; }
  nav ul { flex-direction: column; gap: 0; }
  nav ul li a { padding: 0.65rem 1.5rem; font-size: 0.9rem; border-radius: 0; }

  /* Layout */
  main { padding: 0 1rem; gap: 1rem; }
  .card { padding: 1.5rem 1.25rem; }
  .header-inner { padding: 0 1rem; }

  /* Profile */
  .profile-body { flex-direction: column-reverse; gap: 1.5rem; }
  .profile-photo-wrap { width: 120px; }
  .profile-photo-wrap img { width: 120px; height: 150px; }

  /* Two-col card stacks */
  .two-col-card { flex-direction: column; padding: 1.5rem 0; }
  .col-divider { width: auto; height: 1px; margin: 0 1.25rem; }

  /* News groups narrow */
  .news-group { gap: 0.75rem; }
  .news-year { width: 30px; font-size: 0.8rem; }
  .news-item { flex-direction: column; gap: 0.2rem; }
  .news-date { padding-top: 0; }
}

/* ── Print ───────────────────────────────────────────────────── */
@media print {
  :root {
    --bg-page:        #fff;
    --bg-card:        #fff;
    --border-card:    #ccc;
    --border-divider: #ddd;
    --border-subtle:  #ddd;
    --text-h:         #000;
    --text-body:      #111;
    --text-secondary: #222;
    --text-muted:     #444;
    --text-faint:     #555;
    --text-faintest:  #666;
    --link:           #000;
    --shadow-card:    none;
  }

  #site-header, footer { display: none; }
  main { margin: 0; padding: 0; gap: 0.5rem; }
  .card { border: none; box-shadow: none; padding: 0.75rem 0; page-break-inside: avoid; break-inside: avoid; }

  .social-links a::after { content: " <" attr(href) ">"; font-size: 0.72rem; color: #555; }

  a { color: #000; text-decoration: none; }

  .pub-card, .news-item, .edu-item, .teaching-item {
    page-break-inside: avoid;
    break-inside: avoid;
  }

  .sk { display: none; }
  nav { display: none; }
  .nav-toggle { display: none; }
}