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

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

:root {
  --bg: #fafafa;
  --surface: #ffffff;
  --border: #e8e8e8;
  --text: #1a1a1a;
  --muted: #777;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --tag-bg: #f1f5f9;
  --tag-text: #475569;
  --max-width: 800px;
  --shadow: 0 1px 3px rgba(0,0,0,0.07), 0 4px 12px rgba(0,0,0,0.04);
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  font-size: 15.5px;
}

a {
  color: var(--accent);
  text-decoration: none;
}
a:hover { text-decoration: underline; color: var(--accent-hover); }

/* ── Header ── */
header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 3rem 1.5rem;
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 2rem;
}

.avatar {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  object-fit: cover;
  box-shadow: 0 0 0 3px var(--bg), 0 0 0 5px var(--border);
  flex-shrink: 0;
}

.header-text h1 {
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 0.25rem;
}

.affiliation {
  color: var(--muted);
  font-size: 0.9rem;
  font-weight: 400;
  margin-bottom: 1rem;
  letter-spacing: 0.01em;
}

.header-links {
  display: flex;
  gap: 0.5rem;
}

.header-links a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--bg);
  color: #444;
  transition: all 0.15s ease;
  box-shadow: var(--shadow);
}
.header-links a:hover {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
  text-decoration: none;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(37,99,235,0.25);
}

/* ── Main ── */
main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 3rem 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 3rem;
}

section h2 {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
  margin-bottom: 1.25rem;
}

#about p {
  font-size: 1rem;
  color: #333;
  max-width: 660px;
  line-height: 1.75;
}

/* ── Research interests tags ── */
.tags {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tags li {
  background: var(--tag-bg);
  color: var(--tag-text);
  padding: 0.3rem 0.85rem;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 500;
  border: 1px solid var(--border);
}

/* ── Papers ── */
.paper {
  display: grid;
  grid-template-columns: 3.5rem 1fr;
  gap: 1rem;
  padding: 1.4rem 1.5rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  margin-bottom: 0.85rem;
  box-shadow: var(--shadow);
  transition: box-shadow 0.15s ease, transform 0.15s ease;
}

.paper:hover {
  box-shadow: 0 4px 20px rgba(0,0,0,0.09);
  transform: translateY(-1px);
}

.paper-meta {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--muted);
  padding-top: 0.2rem;
  text-align: right;
}

.paper-title {
  font-size: 0.975rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
  line-height: 1.45;
  color: var(--text);
}

.paper-authors {
  font-size: 0.825rem;
  color: var(--muted);
  margin-bottom: 0.15rem;
}

.paper-venue {
  font-size: 0.825rem;
  font-style: italic;
  color: var(--muted);
  margin-bottom: 0.75rem;
}

.paper-links {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
}

.btn {
  font-size: 0.75rem;
  font-weight: 500;
  padding: 0.2rem 0.7rem;
  border: 1px solid var(--border);
  border-radius: 5px;
  color: var(--muted);
  background: var(--bg);
  transition: all 0.15s ease;
}
.btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: #eff6ff;
  text-decoration: none;
}

/* ── Contact ── */
#contact p {
  color: #555;
  margin-bottom: 0.85rem;
}

.contact-btn {
  font-size: 0.85rem;
  font-weight: 500;
  padding: 0.45rem 1.1rem;
  cursor: pointer;
  border: 1px solid var(--border);
  border-radius: 8px;
  background: var(--surface);
  color: var(--text);
  box-shadow: var(--shadow);
  transition: all 0.15s ease;
}
.contact-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: #eff6ff;
}

/* ── Footer ── */
footer {
  text-align: center;
  font-size: 0.78rem;
  color: #bbb;
  padding: 2rem 1.5rem;
  border-top: 1px solid var(--border);
  letter-spacing: 0.02em;
}

/* ── Divider between sections ── */
section + section {
  padding-top: 0;
}

/* ── Responsive ── */
@media (max-width: 560px) {
  .header-inner { flex-direction: column; align-items: flex-start; gap: 1.25rem; }
  .paper { grid-template-columns: 1fr; }
  .paper-meta { text-align: left; }
}