/* =========================================================================
   Prof. Chongsheng Zhang — Academic Homepage Stylesheet
   ========================================================================= */

:root {
  --color-bg: #f4f4f1;
  --color-card: #ffffff;
  --color-text: #1a1a1a;
  --color-text-soft: #555;
  --color-text-muted: #888;
  --color-link: #1a4ed8;
  --color-link-hover: #0a2db8;
  --color-border: #e5e5e0;
  --color-accent: #b8860b;
  --color-tag-bg: #efefe9;

  --font-serif: 'Crimson Pro', Georgia, 'Times New Roman', serif;
  --font-sans: 'Inter Tight', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;

  --radius: 6px;
  --shadow-card: 0 1px 3px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.03);
  --max-width: 920px;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 {
  font-family: var(--font-serif);
  font-weight: 600;
  letter-spacing: -0.01em;
  margin: 0 0 0.5em 0;
}
h1 { font-size: 2.2rem; line-height: 1.15; }
h2 { font-size: 1.5rem; border-bottom: 1px solid var(--color-border); padding-bottom: 0.4rem; margin-bottom: 1rem; }
h3 { font-size: 1.15rem; }
p  { margin: 0 0 1em 0; }
strong { font-weight: 600; }
small { color: var(--color-text-muted); font-size: 0.85rem; }

a { color: var(--color-link); text-decoration: none; transition: color 0.15s ease; }
a:hover { color: var(--color-link-hover); text-decoration: underline; }

.page { max-width: var(--max-width); margin: 0 auto; padding: 1.5rem 1rem 4rem; }

.topnav {
  background: var(--color-card);
  border-radius: var(--radius);
  padding: 0.85rem 1.5rem;
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow-card);
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 0.4rem 1.2rem;
  font-family: var(--font-serif);
  font-size: 1.05rem;
}
.topnav a { font-weight: 600; position: relative; padding: 0.15rem 0; }
.topnav a.active { color: var(--color-text); pointer-events: none; }
.topnav a.active::after {
  content: ''; position: absolute;
  left: 0; right: 0; bottom: -3px;
  height: 2px; background: var(--color-accent);
}
.topnav .sep { color: var(--color-text-muted); user-select: none; }

.card {
  background: var(--color-card);
  border-radius: var(--radius);
  padding: 2rem 2.25rem;
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow-card);
}
@media (max-width: 640px) { .card { padding: 1.4rem 1.25rem; } }

.profile {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 2rem;
  align-items: start;
}
.profile-photo {
  width: 100%;
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
}
.profile-info h1 { margin-bottom: 0.4rem; }
.profile-info .chinese-name { font-size: 1.6rem; color: var(--color-text-soft); font-weight: 500; margin-left: 0.3rem; }
.profile-info .title-line { font-size: 1.05rem; color: var(--color-text-soft); margin: 0.2rem 0; }
.profile-info .email { margin-top: 0.6rem; color: var(--color-text-soft); }

.profile-links {
  margin-top: 1rem;
  display: flex;
  gap: 0.7rem;
  flex-wrap: wrap;
  align-items: center;
}
.profile-links a { font-weight: 600; font-size: 0.95rem; }

.btn-cv {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: var(--color-accent);
  color: #fff !important;
  padding: 0.5rem 1rem;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.92rem;
  transition: background 0.15s;
  text-decoration: none !important;
}
.btn-cv:hover { background: #9a700a; }

@media (max-width: 640px) {
  .profile { grid-template-columns: 1fr; gap: 1.2rem; }
  .profile-photo { max-width: 200px; margin: 0 auto; display: block; }
  .profile-info { text-align: center; }
  .profile-links { justify-content: center; }
}

.news-list { list-style: none; padding: 0; margin: 0; }
.news-list li {
  padding: 0.45rem 0;
  border-bottom: 1px dashed var(--color-border);
  font-size: 0.98rem;
}
.news-list li:last-child { border-bottom: none; }
.news-date {
  display: inline-block;
  font-feature-settings: 'tnum';
  color: var(--color-accent);
  font-weight: 600;
  font-size: 0.88rem;
  min-width: 88px;
  margin-right: 0.5rem;
}

.tag-list {
  display: flex; gap: 0.5rem; flex-wrap: wrap;
  list-style: none; padding: 0; margin: 0.5rem 0 0 0;
}
.tag {
  background: var(--color-tag-bg);
  border-radius: 999px;
  padding: 0.3rem 0.85rem;
  font-size: 0.88rem;
  color: var(--color-text-soft);
  font-weight: 500;
}

.stats {
  display: flex; gap: 1.5rem;
  margin-top: 1rem; padding-top: 1rem;
  border-top: 1px solid var(--color-border);
  flex-wrap: wrap;
}
.stat { font-size: 0.92rem; color: var(--color-text-soft); }
.stat strong {
  font-family: var(--font-serif);
  font-size: 1.4rem;
  display: block;
  line-height: 1;
  margin-bottom: 0.2rem;
}

.research-theme {
  margin-bottom: 2rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--color-border);
}
.research-theme:last-child { border-bottom: none; margin-bottom: 0; padding-bottom: 0; }
.research-theme h3 { color: var(--color-accent); margin-bottom: 0.4rem; }
.research-theme .theme-papers { margin-top: 0.6rem; font-size: 0.93rem; color: var(--color-text-soft); }

.year-section { margin-bottom: 1.8rem; }
.year-section h3 {
  font-size: 1.35rem;
  color: var(--color-accent);
  border-bottom: 1px solid var(--color-border);
  padding-bottom: 0.3rem;
  margin-bottom: 0.8rem;
}
.pub-list {
  list-style: none; padding: 0; margin: 0;
  counter-reset: pub-counter;
}
.pub-list li {
  padding: 0.7rem 0 0.7rem 2.2rem;
  border-bottom: 1px solid var(--color-border);
  position: relative;
  counter-increment: pub-counter;
}
.pub-list li::before {
  content: counter(pub-counter) ".";
  position: absolute;
  left: 0; top: 0.7rem;
  font-family: var(--font-serif);
  font-weight: 600;
  color: var(--color-text-muted);
  width: 1.8rem;
  text-align: right;
}
.pub-list li:last-child { border-bottom: none; }
.pub-title { font-weight: 600; display: block; margin-bottom: 0.15rem; line-height: 1.4; }
.pub-authors { font-size: 0.93rem; color: var(--color-text-soft); display: block; margin-bottom: 0.15rem; }
.pub-authors .self { font-weight: 600; color: var(--color-text); }
.pub-venue { font-size: 0.92rem; color: var(--color-text-muted); font-style: italic; display: block; }
.pub-links { display: inline-block; margin-left: 0.5rem; font-style: normal; }
.pub-links a {
  display: inline-block;
  background: var(--color-tag-bg);
  padding: 0.05rem 0.55rem;
  border-radius: 999px;
  font-size: 0.78rem;
  color: var(--color-text-soft);
  font-weight: 600;
  margin-right: 0.3rem;
  text-decoration: none;
}
.pub-links a:hover { background: var(--color-accent); color: #fff !important; text-decoration: none; }

.loading {
  text-align: center;
  padding: 2rem;
  color: var(--color-text-muted);
  font-style: italic;
}

.coming-soon { text-align: center; padding: 3rem 1rem; color: var(--color-text-muted); }
.coming-soon h2 { border: none; font-size: 1.8rem; color: var(--color-accent); }

.footer {
  text-align: center;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  padding: 1.5rem 0 0.5rem;
}

@media print {
  .topnav, .footer { display: none; }
  body { background: #fff; }
  .card { box-shadow: none; padding: 0.5rem 0; }
}




/* ============ BibTeX Popup ============ */
.bibtex-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.55);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 9999;
  padding: 1rem;
  animation: fadeIn 0.15s ease;
}
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }

.bibtex-popup {
  background: #fff;
  border-radius: var(--radius);
  max-width: 700px;
  width: 100%;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  box-shadow: 0 20px 60px rgba(0,0,0,0.3);
}
.bibtex-popup-header {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--color-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-serif);
  font-size: 1.1rem;
}
.bibtex-close {
  background: none;
  border: none;
  font-size: 1.6rem;
  cursor: pointer;
  color: var(--color-text-muted);
  line-height: 1;
  padding: 0 0.3rem;
}
.bibtex-close:hover { color: var(--color-text); }

.bibtex-content {
  margin: 0;
  padding: 1.25rem;
  overflow: auto;
  background: #f8f8f5;
  font-family: 'Courier New', monospace;
  font-size: 0.85rem;
  white-space: pre-wrap;
  word-break: break-word;
  flex: 1;
  border: none;
}
.bibtex-actions {
  padding: 0.85rem 1.25rem;
  border-top: 1px solid var(--color-border);
  display: flex;
  gap: 0.6rem;
  justify-content: flex-end;
}
.bibtex-actions button {
  padding: 0.5rem 1rem;
  border: 1px solid var(--color-border);
  background: #fff;
  border-radius: var(--radius);
  cursor: pointer;
  font-size: 0.9rem;
  font-family: var(--font-sans);
  transition: all 0.15s ease;
}
.bibtex-actions button:hover {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}