/* ── reset & base ─────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --blue:       #0a3d62;
  --blue-mid:   #1e3799;
  --blue-light: #ebf5ff;
  --accent:     #e55039;
  --text:       #1a1a2e;
  --muted:      #555;
  --border:     #dde4ee;
  --bg:         #f7f9fc;
  --white:      #ffffff;
  --radius:     8px;
  --shadow:     0 2px 12px rgba(10,61,98,.10);
  --transition: .2s ease;
}

html { scroll-behavior: smooth; }

body {
  font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text);
  background: var(--bg);
}

a { color: var(--blue-mid); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--accent); }

/* ── navbar ───────────────────────────────────────────────── */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--blue);
  box-shadow: 0 2px 8px rgba(0,0,0,.25);
}
.nav-inner {
  max-width: 1080px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  height: 56px;
}
.nav-brand { font-size: 18px; font-weight: 700; color: var(--white); }
.nav-links { display: flex; gap: 28px; list-style: none; }
.nav-links a { color: rgba(255,255,255,.85); font-size: 14px; font-weight: 500; }
.nav-links a:hover { color: var(--white); }

/* ── hero / profile ───────────────────────────────────────── */
.hero {
  background: linear-gradient(135deg, var(--blue) 0%, var(--blue-mid) 100%);
  color: var(--white);
  padding: 64px 24px;
}
.hero-inner {
  max-width: 1080px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 48px;
}
.hero-avatar {
  flex-shrink: 0;
  width: 160px;
  height: 160px;
  border-radius: 50%;
  border: 4px solid rgba(255,255,255,.4);
  object-fit: cover;
  background: rgba(255,255,255,.15);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 64px;
  overflow: hidden;
}
.hero-avatar img { width: 100%; height: 100%; object-fit: cover; }
.hero-info h1 { font-size: 36px; font-weight: 700; margin-bottom: 4px; }
.hero-info .title { font-size: 18px; opacity: .85; margin-bottom: 12px; }
.hero-info .affiliation { font-size: 15px; opacity: .75; margin-bottom: 16px; }
.hero-tags { display: flex; flex-wrap: wrap; gap: 8px; }
.tag {
  background: rgba(255,255,255,.18);
  border: 1px solid rgba(255,255,255,.3);
  border-radius: 20px;
  padding: 3px 14px;
  font-size: 13px;
}
.hero-contact { margin-top: 18px; display: flex; gap: 16px; flex-wrap: wrap; }
.hero-contact a {
  color: rgba(255,255,255,.9);
  font-size: 14px;
  display: flex;
  align-items: center;
  gap: 5px;
}
.hero-contact a:hover { color: var(--white); }

/* ── page layout ──────────────────────────────────────────── */
.container { max-width: 1080px; margin: 0 auto; padding: 0 24px; }
main { padding: 48px 0; }

/* ── section ──────────────────────────────────────────────── */
section { margin-bottom: 56px; }
.section-title {
  font-size: 22px;
  font-weight: 700;
  color: var(--blue);
  padding-bottom: 10px;
  border-bottom: 3px solid var(--blue);
  margin-bottom: 24px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.section-title .icon { font-size: 20px; }

/* ── about ────────────────────────────────────────────────── */
.about-text { color: var(--text); max-width: 800px; }
.about-text p + p { margin-top: 12px; }

/* ── research interests ───────────────────────────────────── */
.interest-grid { display: flex; flex-wrap: wrap; gap: 10px; }
.interest-tag {
  background: var(--blue-light);
  color: var(--blue);
  border: 1px solid #c0d8f0;
  border-radius: 20px;
  padding: 5px 16px;
  font-size: 14px;
  font-weight: 500;
}

/* ── timeline (experience & education) ───────────────────── */
.timeline { position: relative; padding-left: 28px; }
.timeline::before {
  content: "";
  position: absolute;
  left: 7px; top: 8px; bottom: 8px;
  width: 2px;
  background: var(--border);
}
.timeline-item { position: relative; margin-bottom: 28px; }
.timeline-item::before {
  content: "";
  position: absolute;
  left: -25px; top: 8px;
  width: 12px; height: 12px;
  border-radius: 50%;
  background: var(--blue);
  border: 2px solid var(--white);
  box-shadow: 0 0 0 2px var(--blue);
}
.timeline-meta {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 4px;
  flex-wrap: wrap;
}
.timeline-year {
  font-size: 13px;
  color: var(--muted);
  background: var(--blue-light);
  padding: 1px 8px;
  border-radius: 4px;
  white-space: nowrap;
}
.timeline-role { font-weight: 700; font-size: 16px; color: var(--blue); }
.timeline-org { font-size: 15px; color: var(--text); }
.timeline-desc { font-size: 14px; color: var(--muted); margin-top: 4px; }

/* ── courses ──────────────────────────────────────────────── */
.course-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 18px;
}
.course-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
}
.course-card:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(10,61,98,.14); }
.course-level {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .5px;
  padding: 2px 8px;
  border-radius: 4px;
  margin-bottom: 8px;
}
.level-ug { background: #dff0d8; color: #2d6a2d; }
.level-pg { background: #dce8fb; color: #1a4b8e; }
.course-name { font-size: 16px; font-weight: 700; color: var(--blue); margin-bottom: 6px; }
.course-desc { font-size: 14px; color: var(--muted); }
.course-meta { margin-top: 10px; font-size: 13px; color: var(--muted); display: flex; gap: 12px; }

/* ── publications ─────────────────────────────────────────── */
.pub-filters { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 20px; }
.filter-btn {
  border: 1px solid var(--border);
  background: var(--white);
  color: var(--muted);
  padding: 5px 14px;
  border-radius: 20px;
  font-size: 13px;
  cursor: pointer;
  transition: all var(--transition);
}
.filter-btn:hover, .filter-btn.active {
  background: var(--blue);
  color: var(--white);
  border-color: var(--blue);
}
.pub-list { display: flex; flex-direction: column; gap: 16px; }
.pub-item {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  box-shadow: var(--shadow);
  border-left: 4px solid var(--blue-mid);
}
.pub-item[data-type="book"] { border-left-color: #8e44ad; }
.pub-item[data-type="conference"] { border-left-color: #16a085; }
.pub-title { font-size: 16px; font-weight: 700; color: var(--blue); margin-bottom: 6px; }
.pub-authors { font-size: 14px; color: var(--muted); margin-bottom: 4px; }
.pub-authors strong { color: var(--text); }
.pub-venue { font-size: 14px; font-style: italic; color: var(--blue-mid); margin-bottom: 8px; }
.pub-links { display: flex; gap: 10px; flex-wrap: wrap; }
.pub-link {
  font-size: 12px;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 4px;
  border: 1px solid;
}
.pub-link.pdf  { border-color: var(--accent); color: var(--accent); }
.pub-link.doi  { border-color: var(--blue-mid); color: var(--blue-mid); }
.pub-link.code { border-color: #27ae60; color: #27ae60; }
.pub-link:hover { opacity: .75; }
.pub-badge {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  padding: 1px 7px;
  border-radius: 4px;
  margin-left: 8px;
  vertical-align: middle;
}
.badge-journal    { background: #dce8fb; color: #1a4b8e; }
.badge-conference { background: #d5f5e3; color: #1d6b3b; }
.badge-book       { background: #e8daef; color: #6c3483; }

/* ── service ──────────────────────────────────────────────── */
.service-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
}
.service-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 20px;
  box-shadow: var(--shadow);
}
.service-card h4 { color: var(--blue); font-size: 15px; margin-bottom: 8px; }
.service-card ul { list-style: none; }
.service-card ul li {
  font-size: 14px;
  color: var(--muted);
  padding: 3px 0;
  border-bottom: 1px dashed var(--border);
}
.service-card ul li:last-child { border-bottom: none; }

/* ── footer ───────────────────────────────────────────────── */
footer {
  background: var(--blue);
  color: rgba(255,255,255,.75);
  text-align: center;
  padding: 24px;
  font-size: 14px;
}
footer a { color: rgba(255,255,255,.85); }

/* ── responsive ───────────────────────────────────────────── */
@media (max-width: 680px) {
  .hero-inner { flex-direction: column; text-align: center; }
  .hero-tags, .hero-contact { justify-content: center; }
  .nav-links { gap: 16px; }
  .nav-brand { font-size: 15px; }
}