/* Refined style: yuzhench cover identity + Sitzmann layout */
:root {
  --primary: #2b7de9;
  --text: #202124;
  --gray: #5f6368;
  --light-gray: #9aa0a6;
  --border: #e8eaed;
  --bg: #ffffff;
  --bg-alt: #f8f9fa;
  --award: #d93025;
}
* , *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 64px; }
body {
  margin: 0;
  font-family: "Inter", "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.65;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}
a { color: var(--primary); text-decoration: none; transition: color .15s; }
a:hover { text-decoration: underline; }
img, video { max-width: 100%; }

.wrap { max-width: 860px; margin: 0 auto; padding: 0 24px; }

/* hero (Sitzmann-style: text left, portrait right) */
.hero { padding-top: 56px; }
.hero__row {
  display: flex; align-items: center; justify-content: space-between;
  gap: 40px; flex-wrap: wrap;
}
.hero__text { flex: 1 1 460px; min-width: 0; }
.avatar {
  flex: 0 0 auto;
  width: 190px; height: 190px; border-radius: 50%;
  overflow: hidden; background: var(--bg-alt);
}
.avatar img { width: 100%; height: 100%; object-fit: cover; display: block; }
.hero h1 { margin: 0 0 4px; font-size: 34px; font-weight: 700; letter-spacing: -.5px; }
.hero .role { color: var(--gray); font-size: 16px; font-weight: 500; margin: 0 0 4px; }
.hero .meta { color: var(--light-gray); font-size: 14px; margin: 0; }
.hero .meta i { margin-right: 4px; }
.chips { display: flex; flex-wrap: wrap; gap: 10px; margin: 18px 0 0; }
.chip {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 9px 16px; font-size: 14px; font-weight: 500;
  color: var(--text); border: 1px solid var(--border); border-radius: 9px;
  background: var(--bg); transition: background .15s, border-color .15s;
}
.chip:hover { background: var(--bg-alt); border-color: #d2d5da; text-decoration: none; }
.chip i { color: var(--gray); }
.bio { margin-top: 22px; color: #3c4043; }
.bio p { margin: 0 0 12px; }

/* top brand bar (Sitzmann-style) */
.topbar {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,.94); backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
}
.topbar .wrap {
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
}
.topbar .brand {
  font-size: 17px; font-weight: 700; letter-spacing: -.3px; color: var(--text);
  white-space: nowrap; padding: 14px 0;
}
.topbar .brand:hover { text-decoration: none; color: var(--primary); }
.topbar ul {
  display: flex; gap: 2px; list-style: none; margin: 0; padding: 0;
  overflow-x: auto; scrollbar-width: none;
}
.topbar ul a {
  display: block; padding: 16px 11px 14px; font-size: 14.5px; font-weight: 500;
  color: var(--text); border-bottom: 2px solid transparent; white-space: nowrap;
}
.topbar ul a:hover { color: var(--primary); text-decoration: none; }
.topbar ul a.active { color: var(--primary); border-color: var(--primary); }

/* sections */
section { padding: 44px 0 8px; }
.section-title {
  display: inline-block; margin: 0 0 6px; font-size: 25px; font-weight: 700;
  letter-spacing: -.4px; padding-bottom: 6px; border-bottom: 3px solid var(--primary);
}
.section-sub { color: var(--gray); font-size: 15px; margin: 10px 0 8px; }

/* research cards */
.research-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-top: 20px; }
.research-card {
  border: 1px solid var(--border); border-radius: 14px; padding: 20px;
  background: var(--bg); transition: box-shadow .15s;
}
.research-card:hover { box-shadow: 0 3px 14px rgba(0,0,0,.06); }
.research-card i {
  width: 36px; height: 36px; line-height: 36px; text-align: center;
  font-size: 16px; border-radius: 9px; background: var(--bg-alt); color: var(--primary);
}
.research-card h3 { margin: 12px 0 6px; font-size: 16px; font-weight: 600; }
.research-card p { margin: 0; font-size: 14px; color: var(--gray); line-height: 1.55; }

/* publication rows */
.pub { display: flex; gap: 22px; padding: 24px 0; border-bottom: 1px solid var(--border); }
.pub:last-child { border-bottom: none; }
.pub__thumb { flex: 0 0 200px; }
.pub__thumb img, .pub__thumb video {
  width: 200px; height: 134px; object-fit: cover; display: block;
  border-radius: 8px; border: 1px solid var(--border); background: var(--bg-alt);
}
.pub__thumb img.contain { object-fit: contain; padding: 6px; background: #fff; }
.pub__body { flex: 1; min-width: 0; }
.pub__title { margin: 0; font-size: 17px; font-weight: 600; line-height: 1.4; }
.pub__title a { color: var(--text); }
.pub__title a:hover { color: var(--primary); text-decoration: none; }
.pub__authors { margin: 5px 0 0; font-size: 14px; color: var(--gray); line-height: 1.5; }
.pub__authors b { color: var(--text); font-weight: 600; }
.pub__venue { margin: 5px 0 0; font-size: 14px; }
.pub__venue strong { font-weight: 700; }
.pub__award { color: var(--award); font-weight: 600; }
.pub__award i { margin-right: 4px; }
.pub__links { margin: 7px 0 0; font-size: 14px; font-weight: 500; }
.pub__links a { margin-right: 16px; }
.pub__stat {
  display: inline-flex; align-items: center; gap: 5px;
  margin-right: 12px; padding: 2px 9px;
  font-size: 12.5px; font-weight: 500; color: var(--gray) !important;
  border: 1px solid var(--border); border-radius: 20px; background: var(--bg-alt);
}
.pub__stat:hover { text-decoration: none; border-color: #d2d5da; color: var(--text) !important; }
.pub__stat i { font-size: 11px; color: var(--light-gray); }
.pub__stat i.fa-star { color: #f2a33c; }

/* awards */
.award-row {
  display: flex; gap: 14px; align-items: baseline;
  padding: 13px 0; border-bottom: 1px solid var(--border); font-size: 15px;
}
.award-row:last-child { border-bottom: none; }
.award-row .venue { flex: 0 0 300px; font-weight: 600; }
.award-row .desc { color: var(--gray); font-style: italic; }

/* students */
.students-head { display: flex; align-items: baseline; justify-content: space-between; gap: 16px; flex-wrap: wrap; }
.students-toggle { display: inline-flex; border: 1px solid var(--border); border-radius: 9px; overflow: hidden; }
.toggle-btn {
  padding: 8px 18px; font-size: 14px; font-weight: 500; font-family: inherit;
  color: var(--gray); background: var(--bg); border: none; cursor: pointer;
  transition: background .15s, color .15s;
}
.toggle-btn + .toggle-btn { border-left: 1px solid var(--border); }
.toggle-btn:hover { color: var(--text); }
.toggle-btn.active { background: var(--primary); color: #fff; }
.students-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 4px 32px; margin-top: 14px; }
.students-grid[hidden] { display: none; }
.student {
  display: flex; justify-content: space-between; align-items: baseline; gap: 12px;
  padding: 11px 0; border-bottom: 1px solid var(--border); font-size: 15px;
}
.student .school { color: var(--gray); font-size: 13.5px; white-space: nowrap; }

/* footer */
footer { margin-top: 56px; padding: 36px 0 44px; border-top: 1px solid var(--border); background: var(--bg-alt); }
footer .chips { justify-content: center; margin: 0 0 18px; }
footer .chip { background: var(--bg); }
footer .copyright { text-align: center; color: var(--light-gray); font-size: 13.5px; }

@media (max-width: 760px) {
  .cover img { height: 220px; }
  .research-grid { grid-template-columns: 1fr; }
  .students-grid { grid-template-columns: 1fr; }
  .pub { flex-direction: column; gap: 14px; }
  .pub__thumb, .pub__thumb img, .pub__thumb video { width: 100%; flex: none; }
  .pub__thumb img, .pub__thumb video { height: auto; aspect-ratio: 3/2; }
  .award-row { flex-direction: column; gap: 2px; }
  .award-row .venue { flex: none; }
  .hero h1 { font-size: 26px; }
}