/* ============================================================
   Qing Wu — Personal Academic Homepage
   Clean editorial style, single accent color, Inter throughout.
   ============================================================ */

:root {
  --max-width: 920px;
  --gutter: 1.5rem;

  --font-sans:    "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --font-display: "Space Grotesk", "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --font-mono:    "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  /* Light palette — warm cream paper */
  --bg:           #faf7f1;
  --bg-soft:      #f3eee3;
  --bg-elev:      #fdfbf6;
  --rule:         #cdc6b5;
  --border:       #e3dccb;
  --text:         #1f1c17;
  --text-soft:    #524a3d;
  --text-mute:    #8a8170;

  --accent:       #c0392b;
  --accent-2:     #7a3b2a;
  --accent-soft:  rgba(192,57,43,.10);
  --accent-link:  #9a2b1f;
  --gold:         #b48a3e;

  --shadow-sm:    0 1px 2px rgba(40,30,10,.04);
  --shadow:       0 2px 4px rgba(40,30,10,.04), 0 10px 30px rgba(40,30,10,.06);
  --shadow-hover: 0 4px 8px rgba(40,30,10,.07), 0 18px 40px rgba(40,30,10,.10);
}

[data-theme="dark"] {
  --bg:           #15131a;
  --bg-soft:      #1c1924;
  --bg-elev:      #1f1c28;
  --rule:         #3a3548;
  --border:       #2b2738;
  --text:         #ece7d8;
  --text-soft:    #b6ad97;
  --text-mute:    #7d7460;

  --accent:       #e07a5f;
  --accent-2:     #f2cc8f;
  --accent-soft:  rgba(224,122,95,.14);
  --accent-link:  #f2a48a;
  --gold:         #d4a85a;

  --shadow-sm:    0 1px 2px rgba(0,0,0,.35);
  --shadow:       0 2px 4px rgba(0,0,0,.30), 0 16px 40px rgba(0,0,0,.45);
  --shadow-hover: 0 4px 8px rgba(0,0,0,.40), 0 24px 50px rgba(0,0,0,.55);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16.5px;
  line-height: 1.7;
  color: var(--text);
  background-color: var(--bg);
  background-image:
    url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='200' height='200'><filter id='n'><feTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='2' stitchTiles='stitch'/><feColorMatrix values='0 0 0 0 0  0 0 0 0 0  0 0 0 0 0  0 0 0 0.06 0'/></filter><rect width='100%' height='100%' filter='url(%23n)'/></svg>");
  background-attachment: fixed;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a {
  color: var(--accent-link);
  text-decoration: none;
  border-bottom: 1px solid color-mix(in srgb, var(--accent-link) 30%, transparent);
  transition: color .15s ease, border-color .15s ease, background .15s ease;
}
a:hover { color: var(--accent); border-bottom-color: var(--accent); }

::selection { background: var(--accent-soft); color: var(--accent-2); }
[data-theme="dark"] ::selection { color: var(--text); }

/* ===== Navbar ===== */
.navbar {
  position: sticky; top: 0; z-index: 100;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: .85rem var(--gutter);
  display: flex; align-items: center; gap: 1rem;
}
.nav-brand {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1.1rem;
  letter-spacing: -.01em;
  color: var(--text);
  border-bottom: none;
  display: inline-flex;
  align-items: center;
  gap: .55rem;
}
.nav-logo {
  width: 26px;
  height: 26px;
  object-fit: contain;
  display: block;
}
.nav-brand:hover { color: var(--accent); }

.nav-links { margin-left: auto; display: flex; gap: 1.4rem; flex-wrap: wrap; }
.nav-links a {
  position: relative;
  color: var(--text-soft);
  font-size: .82rem;
  font-weight: 500;
  letter-spacing: .08em;
  text-transform: uppercase;
  border-bottom: none;
  padding-bottom: 2px;
}
.nav-links a::after {
  content: ""; position: absolute;
  left: 0; right: 100%; bottom: -2px;
  height: 1px; background: var(--accent);
  transition: right .2s ease;
}
.nav-links a:hover { color: var(--text); }
.nav-links a:hover::after { right: 0; }

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-soft);
  width: 36px; height: 36px;
  border-radius: 50%;
  cursor: pointer;
  display: inline-flex; align-items: center; justify-content: center;
  transition: background .15s ease, color .15s ease, border-color .15s ease, transform .2s ease;
}
.theme-toggle:hover {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: var(--accent);
  transform: rotate(15deg);
}

/* ===== Layout / sections ===== */
main { max-width: var(--max-width); margin: 0 auto; padding: 0 var(--gutter); }

.section { padding: 2.25rem 0 1rem; position: relative; }

.section-title {
  font-family: var(--font-display);
  font-size: 1.65rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.2;
  margin: 0 0 .4rem;
  color: var(--text);
  display: flex;
  align-items: baseline;
  gap: .75rem;
}
.section-title::before {
  content: "§ " attr(data-num);
  font-family: var(--font-mono);
  font-size: .7rem;
  font-weight: 500;
  letter-spacing: .14em;
  color: var(--accent);
  text-transform: uppercase;
  padding: .25rem .55rem;
  border: 1px solid var(--accent);
  border-radius: 999px;
  flex-shrink: 0;
  line-height: 1;
  align-self: center;
}
.section-title:not([data-num])::before { display: none; }
.section-title::after {
  content: ""; flex: 1;
  height: 1px; background: var(--rule);
  margin-left: .5rem;
  align-self: center;
}

.section-sub {
  color: var(--text-mute);
  font-size: .92rem;
  font-style: italic;
  margin: .25rem 0 1.5rem;
}

/* ===== Hero ===== */
.hero { padding-top: 3rem; padding-bottom: 1.5rem; }

.hero-grid {
  display: grid;
  grid-template-columns: 1fr 230px;
  gap: 3rem;
  align-items: start;
}
.hero-text h1 {
  font-family: var(--font-display);
  font-size: clamp(2.4rem, 5.5vw, 3rem);
  font-weight: 600;
  letter-spacing: -0.035em;
  line-height: 1.05;
  margin: 0 0 1rem;
  color: var(--text);
}
.hero-text h1 .cn {
  font-family: var(--font-display);
  font-weight: 500;
  color: var(--accent);
  font-size: 0.72em;
  margin-left: .45rem;
  letter-spacing: 0;
}
.hero-text .tagline {
  font-family: var(--font-mono);
  font-size: .82rem;
  letter-spacing: .04em;
  color: var(--text-soft);
  text-transform: uppercase;
  margin: 0 0 1.5rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--rule);
  position: relative;
}
.hero-text .tagline::after {
  content: "";
  position: absolute;
  left: 0; bottom: -1px;
  width: 64px;
  height: 3px;
  background: var(--accent);
}
.hero-text p { margin: 1rem 0; color: var(--text); }
.hero-text strong { font-weight: 600; color: var(--text); }

.topic-list {
  margin: .75rem 0 0 1.5rem;
  padding: 0;
  list-style: none;
}
.topic-list li {
  position: relative;
  padding: 0 0 0 1.4rem;
  color: var(--text);
  font-size: .98rem;
  line-height: 1.7;
}
.topic-list li::before {
  content: "›";
  position: absolute;
  left: 0; top: 0;
  color: var(--accent);
  font-weight: 600;
  font-size: 1.15rem;
  line-height: 1.5;
}

/* ===== Hero photo + social icons stacked under ===== */
.hero-photo { display: flex; flex-direction: column; align-items: center; gap: 1rem; position: relative; }
.hero-photo::before {
  /* decorative offset frame behind the photo */
  content: "";
  position: absolute;
  top: 12px; left: 50%;
  transform: translateX(calc(-50% + 12px));
  width: 100%;
  max-width: 230px;
  aspect-ratio: 1 / 1;
  border: 1.5px solid var(--accent);
  border-radius: 4px;
  z-index: 0;
}
.hero-photo img {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 230px;
  aspect-ratio: 1 / 1;
  object-fit: cover;
  object-position: 95% center;       /* shift framing toward the face on the right side of the photo */
  border-radius: 4px;
  box-shadow: var(--shadow);
}
.photo-caption {
  position: relative;
  z-index: 1;
  margin: 0;
  font-family: var(--font-mono);
  font-size: .72rem;
  color: var(--text-mute);
  word-break: break-all;
  letter-spacing: .02em;
  text-align: center;
}
.photo-caption .at { color: var(--accent); padding: 0 .15em; }

.social-row {
  position: relative;
  z-index: 1;
  display: flex;
  gap: 1.1rem;
  margin-top: .75rem;
  flex-wrap: nowrap;
  justify-content: center;
  align-items: center;
  width: 100%;
  max-width: 230px;
}
.social-row a,
.social-row .social-popup {
  width: auto; height: auto;
  display: inline-flex; align-items: center; justify-content: center;
  border: none;
  border-bottom: none;
  border-radius: 0;
  background: transparent;
  color: var(--text-soft);
  font-size: 2.4rem;
  line-height: 1;
  padding: .1rem;
  cursor: pointer;
  font-family: inherit;
  transition: color .15s ease, transform .15s ease;
  flex-shrink: 0;
}
.social-row a:hover,
.social-row .social-popup:hover {
  color: var(--accent);
  background: transparent;
  border: none;
  transform: translateY(-2px);
  box-shadow: none;
}
[data-theme="dark"] .social-row a:hover { color: var(--accent); }

/* ===== News ===== */
.news-scroll {
  max-height: 280px;
  overflow-y: auto;
  padding-right: .5rem;
}
.news-scroll::-webkit-scrollbar { width: 6px; }
.news-scroll::-webkit-scrollbar-track { background: transparent; }
.news-scroll::-webkit-scrollbar-thumb { background: var(--rule); border-radius: 3px; }
.news-list { list-style: none; margin: 0; padding: 0; }
.news-list li {
  display: grid;
  grid-template-columns: 110px 1fr;
  gap: 1.25rem;
  padding: .55rem 0;
  font-size: .94rem;
  position: relative;
}
.news-list li:last-child { border-bottom: none; }
.news-list li:hover .news-date { color: var(--accent); }
.news-date {
  color: var(--text-mute);
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .02em;
  white-space: nowrap;
  padding-top: 4px;
  transition: color .15s ease;
}
.news-body { color: var(--text); }
.news-body strong { color: var(--accent); font-weight: 600; }

/* ===== Publications ===== */
.pub-list { display: flex; flex-direction: column; gap: 1.25rem; }

.pub {
  display: grid;
  grid-template-columns: 1fr 4fr;
  gap: 0;
  background: var(--bg-soft);             /* card base = darker cream (the new pub-body bg) */
  border: 1px solid var(--border);
  border-radius: 6px;
  overflow: hidden;
  transition: transform .2s ease, box-shadow .25s ease, border-color .2s ease;
  box-shadow: var(--shadow-sm);
}
.pub:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
  border-color: color-mix(in srgb, var(--accent) 30%, var(--border));
}

.pub-thumb {
  display: flex; align-items: center; justify-content: center;
  background: #ffffff;
  overflow: hidden;
  padding: .6rem .55rem;
  border: none;
  cursor: zoom-in;
  position: relative;
  font: inherit;
  color: inherit;
  width: 100%;
  height: 100%;
  min-height: 100px;
}
[data-theme="dark"] .pub-thumb { background: #ffffff; }
.pub-thumb img {
  width: 100%; height: 100%;
  object-fit: cover;             /* crop to fill — the wide-ratio frame is what gives the layout balance */
  transition: transform .4s ease, opacity .15s ease;
  display: block;
}
.pub:hover .pub-thumb img { transform: scale(1.04); }
.pub-thumb::after {
  /* magnifier hint that fades in on hover */
  content: "\f00e";              /* fa-magnifying-glass-plus */
  font-family: "Font Awesome 6 Free";
  font-weight: 900;
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: #fff;
  background: rgba(0,0,0,.35);
  opacity: 0;
  transition: opacity .2s ease;
  pointer-events: none;
}
.pub-thumb:hover::after,
.pub-thumb:focus-visible::after { opacity: 1; }

.pub-body { display: flex; flex-direction: column; gap: .25rem; padding: .75rem 1rem; min-width: 0; }
.pub-venue { display: flex; gap: .45rem; flex-wrap: wrap; margin-bottom: .25rem; align-items: center; }

.badge {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: .64rem;
  font-weight: 500;
  letter-spacing: .07em;
  text-transform: uppercase;
  padding: .15rem .45rem;
  border-radius: 3px;
  background: var(--bg-soft);
  color: var(--text-soft);
  border: 1px solid var(--border);
}
/* Venue (first badge) — same size as other badges, distinguished by color. */
.pub-venue .badge:first-child {
  color: #fff;
  background: var(--accent);
  border-color: var(--accent);
}
[data-theme="dark"] .pub-venue .badge:first-child { color: var(--bg); }

.badge-accent {
  background: var(--gold) !important;
  color: #fff !important;
  border-color: var(--gold) !important;
}
[data-theme="dark"] .badge-accent { color: var(--bg) !important; }

.pub-title {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 600;
  letter-spacing: -0.015em;
  line-height: 1.35;
  margin: .15rem 0;
  color: var(--text);
}
.pub-authors {
  margin: 0;
  color: var(--text-soft);
  font-size: .9rem;
  line-height: 1.5;
}
.pub-authors strong { color: var(--text); font-weight: 600; }
.pub-links {
  margin: .35rem 0 0;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .04em;
  color: var(--text-mute);
}
.pub-links a {
  text-transform: uppercase;
  font-weight: 500;
  letter-spacing: .08em;
}

/* ===== Friends ===== */
.friends-list {
  list-style: none; margin: 0; padding: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
}
.friends-list li {
  position: relative;
  padding: .55rem 0 .55rem 1.5rem;
  color: var(--text-soft);
  font-size: .96rem;
}
.friends-list li:last-child { border-bottom: none; }
.friends-list li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--accent);
  font-family: var(--font-mono);
  transition: transform .15s ease;
}
.friends-list li:hover::before { transform: translateX(4px); }

/* ===== Footer ===== */
.site-footer {
  max-width: var(--max-width);
  margin: 3rem auto 0;
  padding: 1.75rem var(--gutter) 2.5rem;
  color: var(--text-mute);
  font-size: .78rem;
  text-align: center;
  border-top: 1px solid var(--border);
  font-family: var(--font-mono);
  letter-spacing: .04em;
}

/* ===== Lightbox ===== */
.lightbox {
  position: fixed; inset: 0;
  background: rgba(10,8,5,.88);
  -webkit-backdrop-filter: blur(4px);
  backdrop-filter: blur(4px);
  display: flex; align-items: center; justify-content: center;
  z-index: 1000;
  opacity: 0;
  pointer-events: none;
  transition: opacity .2s ease;
  padding: 2rem;
  cursor: zoom-out;
}
.lightbox.is-open { opacity: 1; pointer-events: auto; }
.lightbox img {
  max-width: 92vw;
  max-height: 88vh;
  object-fit: contain;
  border-radius: 6px;
  box-shadow: 0 20px 60px rgba(0,0,0,.5);
  cursor: default;
}
.lightbox.is-qr img {
  max-width: min(82vw, 420px);
  max-height: min(82vh, 420px);
  background: #fff;
  padding: 12px;
}
.lightbox-close {
  position: absolute;
  top: 1rem; right: 1rem;
  width: 44px; height: 44px;
  border-radius: 50%;
  border: 1px solid rgba(255,255,255,.3);
  background: rgba(0,0,0,.4);
  color: #fff;
  font-size: 1.4rem;
  cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: background .15s ease, transform .15s ease;
}
.lightbox-close:hover { background: rgba(0,0,0,.7); transform: rotate(90deg); }

/* ===== Misc ===== */
.loading { color: var(--text-mute); font-size: .9rem; font-style: italic; }

/* ===== Responsive ===== */
@media (max-width: 720px) {
  .hero { padding-top: 2.5rem; }
  .hero-grid { grid-template-columns: 1fr; gap: 2rem; }
  .hero-photo { order: -1; }
  .hero-photo::before {
    top: 8px;
    transform: translateX(calc(-50% + 8px));
    max-width: 180px;
  }
  .hero-photo img { max-width: 180px; }

  .hero-text h1 { font-size: 2.2rem; }

  .section-title { font-size: 1.35rem; gap: .5rem; }
  .section-title::before { font-size: .65rem; padding: .2rem .45rem; }

  .nav-links { gap: 1rem; }
  .nav-links a { font-size: .72rem; letter-spacing: .06em; }

  .pub { grid-template-columns: 1fr 4fr; }
  .pub-body { padding: .85rem 1rem; }
  .pub-title { font-size: 1rem; }
  .pub-thumb { min-height: 130px; padding: .65rem .5rem; }

  .news-list li { grid-template-columns: 1fr; gap: .25rem; }

  .social-row { max-width: 180px; gap: .85rem; }
  .social-row a,
  .social-row .social-popup { font-size: 1.85rem; }
}

@media (max-width: 440px) {
  .pub { grid-template-columns: 1fr; }
  .pub-thumb { aspect-ratio: 16 / 9; }
}