/* ============================================================
   Zhi-Song Liu — Academic Homepage
   Nordic-Refined Aesthetic
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Crimson+Pro:ital,wght@0,300;0,400;0,600;1,300;1,400&family=DM+Sans:wght@300;400;500;600&family=JetBrains+Mono:wght@400&display=swap');

:root {
  --bg:          #f5f4f0;
  --surface:     #ffffff;
  --surface-alt: #f9f8f5;
  --border:      #e4e1d8;
  --navy:        #1a2744;
  --navy-light:  #243560;
  --accent:      #2e5da8;
  --accent-warm: #c0622b;
  --text:        #1e1e1e;
  --text-mid:    #4a4a4a;
  --text-light:  #7a7a7a;
  --tag-bg:      #eef2fb;
  --tag-color:   #2e5da8;
  --shadow-sm:   0 1px 4px rgba(0,0,0,0.06);
  --shadow-md:   0 4px 20px rgba(0,0,0,0.08);
  --radius:      10px;
  --font-serif:  'Crimson Pro', Georgia, serif;
  --font-sans:   'DM Sans', system-ui, sans-serif;
  --font-mono:   'JetBrains Mono', monospace;
  --max-w:       860px;
  --nav-h:       60px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

/* ── NAV ── */
nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  background: rgba(26,39,68,0.97);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  border-bottom: 1px solid rgba(255,255,255,0.07);
}
nav .nav-inner {
  width: 100%;
  max-width: var(--max-w);
  padding: 0 24px;
  display: flex;
  align-items: center;
  gap: 8px;
}
nav .nav-brand {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  color: #fff;
  font-weight: 400;
  letter-spacing: 0.01em;
  margin-right: auto;
  text-decoration: none;
}
nav .nav-brand:hover { text-decoration: none; color: #fff; }
nav a {
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: rgba(255,255,255,0.65);
  text-decoration: none;
  padding: 6px 12px;
  border-radius: 5px;
  transition: color 0.15s, background 0.15s;
}
nav a:hover, nav a.active {
  color: #fff;
  background: rgba(255,255,255,0.1);
  text-decoration: none;
}

/* ── LAYOUT ── */
main {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 48px 24px 80px;
}

section { margin-bottom: 48px; }

/* ── CARD ── */
.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 36px;
  box-shadow: var(--shadow-sm);
}
.card + .card { margin-top: 20px; }

/* ── HERO (profile) ── */
.hero {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 40px;
  align-items: start;
}
.hero-photo {
  width: 200px;
  border-radius: var(--radius);
  display: block;
  border: 1px solid var(--border);
  object-fit: cover;
}
.hero-name {
  font-family: var(--font-serif);
  font-size: 2.4rem;
  font-weight: 600;
  color: var(--navy);
  line-height: 1.2;
  margin-bottom: 4px;
}
.hero-name-zh {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  color: var(--text-mid);
  font-weight: 300;
  margin-left: 10px;
}
.hero-title {
  font-size: 0.97rem;
  color: var(--text-mid);
  margin-top: 10px;
  line-height: 1.6;
}
.hero-title strong { color: var(--navy); font-weight: 600; }
.hero-title a { color: var(--accent); text-decoration: none; }
.hero-title a:hover { text-decoration: underline; }
.hero-email {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--text-mid);
  margin-top: 14px;
}
.social-links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}
.social-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border: 1px solid var(--border);
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--navy);
  text-decoration: none;
  background: var(--surface-alt);
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}
.social-btn:hover {
  background: var(--navy);
  color: #fff;
  border-color: var(--navy);
  text-decoration: none;
}
.social-btn svg { width: 14px; height: 14px; flex-shrink: 0; }

/* ── SECTION HEADER ── */
.section-title {
  font-family: var(--font-serif);
  font-size: 1.45rem;
  font-weight: 600;
  color: var(--navy);
  margin-bottom: 20px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--border);
  display: flex;
  align-items: baseline;
  gap: 12px;
}
.section-title a {
  font-size: 0.8rem;
  font-family: var(--font-sans);
  font-weight: 500;
  color: var(--accent);
  text-decoration: none;
}
.section-title a:hover { text-decoration: underline; }

/* ── BIO TEXT ── */
.bio-text {
  font-family: var(--font-serif);
  font-size: 1.06rem;
  color: var(--text);
  line-height: 1.8;
}
.bio-text + .bio-text { margin-top: 16px; }
.bio-text a { color: var(--accent); text-decoration: none; }
.bio-text a:hover { text-decoration: underline; }

/* ── NEWS ── */
.news-list { list-style: none; display: flex; flex-direction: column; gap: 12px; }
.news-item { display: flex; gap: 16px; align-items: baseline; }
.news-date {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-light);
  white-space: nowrap;
  min-width: 70px;
}
.news-badge {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 2px 7px;
  border-radius: 4px;
  background: var(--tag-bg);
  color: var(--tag-color);
  flex-shrink: 0;
}
.news-badge.warm { background: #fdf0e8; color: var(--accent-warm); }
.news-body { font-size: 0.93rem; color: var(--text); }
.news-body a { color: var(--accent); text-decoration: none; }
.news-body a:hover { text-decoration: underline; }

/* ── PUBLICATIONS ── */
.pub-year-group { margin-bottom: 36px; }
.pub-year {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 400;
  color: var(--text-light);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}
.pub-entry {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 20px;
  padding: 18px 0;
  border-bottom: 1px solid var(--surface-alt);
}
.pub-entry:last-child { border-bottom: none; }
.pub-thumb {
  width: 160px;
  height: 110px;
  object-fit: cover;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--surface-alt);
  display: block;
}
.pub-thumb-placeholder {
  width: 160px;
  height: 110px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: linear-gradient(135deg, #eef2fb, #f5f4f0);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-light);
  font-size: 0.75rem;
  text-align: center;
}
.pub-info {}
.pub-title {
  font-family: var(--font-serif);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--navy);
  line-height: 1.4;
  margin-bottom: 5px;
}
.pub-title a { color: var(--navy); text-decoration: none; }
.pub-title a:hover { color: var(--accent); text-decoration: underline; }
.pub-award {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent-warm);
  background: #fdf0e8;
  padding: 2px 8px;
  border-radius: 4px;
  margin-bottom: 6px;
}
.pub-authors { font-size: 0.88rem; color: var(--text-mid); margin-bottom: 4px; }
.pub-authors strong { color: var(--navy); font-weight: 600; }
.pub-venue { font-size: 0.85rem; color: var(--text-light); font-style: italic; margin-bottom: 10px; }
.pub-links { display: flex; flex-wrap: wrap; gap: 8px; }
.pub-link {
  font-size: 0.78rem;
  font-weight: 500;
  padding: 3px 10px;
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--accent);
  text-decoration: none;
  background: var(--tag-bg);
  transition: background 0.15s, color 0.15s;
}
.pub-link:hover { background: var(--accent); color: #fff; text-decoration: none; border-color: var(--accent); }

/* ── SERVICES ── */
.services-grid { display: grid; gap: 24px; }
.service-block { }
.service-label {
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-light);
  margin-bottom: 8px;
}
.tag-cloud { display: flex; flex-wrap: wrap; gap: 8px; }
.tag {
  font-size: 0.83rem;
  padding: 4px 12px;
  border-radius: 20px;
  border: 1px solid var(--border);
  color: var(--navy);
  background: var(--surface-alt);
}

/* ── OPEN POSITIONS ── */
.positions-box {
  background: linear-gradient(135deg, #eef2fb 0%, #f5f4f0 100%);
  border: 1px solid #c8d5ef;
  border-radius: var(--radius);
  padding: 28px 32px;
}
.positions-box h3 {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  color: var(--navy);
  margin-bottom: 14px;
}
.positions-box p { font-size: 0.93rem; color: var(--text-mid); margin-bottom: 12px; }
.positions-box ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin: 12px 0;
}
.positions-box ul li {
  font-size: 0.9rem;
  color: var(--text-mid);
  padding-left: 16px;
  position: relative;
}
.positions-box ul li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--accent);
  font-size: 0.8rem;
}
.positions-box a { color: var(--accent); text-decoration: none; font-weight: 500; }
.positions-box a:hover { text-decoration: underline; }

/* ── FOOTER ── */
footer {
  text-align: center;
  padding: 32px 24px;
  border-top: 1px solid var(--border);
  font-size: 0.8rem;
  color: var(--text-light);
  background: var(--surface);
}

/* ── RESPONSIVE ── */
@media (max-width: 640px) {
  .hero { grid-template-columns: 1fr; }
  .hero-photo { width: 140px; }
  .pub-entry { grid-template-columns: 1fr; }
  .pub-thumb { width: 100%; height: auto; }
  nav .nav-brand { display: none; }
  nav a { padding: 6px 8px; font-size: 0.75rem; }
}