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

body {
  font-family: 'Inter', 'Segoe UI', Arial, sans-serif;
  background: #ffffff;
  color: #1a1a2e;
  line-height: 1.65;
}

a { color: inherit; text-decoration: none; }

img { display: block; max-width: 100%; }

/* ── Navigation ── */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: #ffffff;
  border-bottom: 1px solid #e8e8e8;
  padding: 0 2rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-brand {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: #1a1a2e;
}

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.nav-links a {
  font-size: 0.9rem;
  font-weight: 500;
  color: #444;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  transition: color 0.2s;
}

.nav-links a:hover { color: #1d4ed8; }

/* ── Hero ── */
.hero {
  position: relative;
  height: 480px;
  overflow: hidden;
}

.hero-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: brightness(0.55);
}

.hero-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
  padding: 0 8%;
}

.hero-overlay h1 {
  font-size: clamp(2rem, 5vw, 3.4rem);
  font-weight: 800;
  color: #ffffff;
  line-height: 1.15;
  letter-spacing: -0.01em;
}

.hero-overlay p {
  margin-top: 0.75rem;
  font-size: 1.1rem;
  color: #d1dff8;
  max-width: 560px;
}

/* ── Section Shell ── */
.section { padding: 5rem 8%; }

.section-label {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: #6b7280;
  margin-bottom: 0.4rem;
}

.section-title {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 800;
  color: #111827;
  margin-bottom: 2.5rem;
}

/* ── About / Profile ── */
.about-grid {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 4rem;
  align-items: start;
}

.about-left { text-align: center; }

.profile-img-wrap {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  overflow: hidden;
  margin: 0 auto 1.25rem;
  border: 4px solid #e5e7eb;
  box-shadow: 0 4px 20px rgba(0,0,0,0.1);
  background: #f3f4f6;
}

.profile-img-wrap img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: top center;
}

.about-name {
  font-size: 1.7rem;
  font-weight: 700;
  font-family: Georgia, 'Times New Roman', serif;
  margin-bottom: 0.2rem;
}

.about-title {
  font-size: 0.85rem;
  color: #1d4ed8;
  font-weight: 500;
}

.about-bio {
  font-size: 1rem;
  color: #374151;
  margin-bottom: 1.25rem;
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1.5rem;
}

.tag {
  padding: 0.3rem 0.85rem;
  border: 1px solid #d1d5db;
  border-radius: 4px;
  font-size: 0.78rem;
  color: #374151;
  background: #f9fafb;
}

.about-github {
  margin-top: 1rem;
  font-size: 0.9rem;
  color: #1d4ed8;
}

/* ── Research Areas ── */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 2rem;
}

.research-card {
  border-radius: 10px;
  overflow: hidden;
  border: 1px solid #e5e7eb;
  background: #fff;
  transition: box-shadow 0.2s, transform 0.2s;
}

.research-card:hover {
  box-shadow: 0 8px 30px rgba(0,0,0,0.1);
  transform: translateY(-2px);
}

.research-card img {
  width: 100%;
  height: 185px;
  object-fit: cover;
}

.research-card-body {
  padding: 1.25rem;
}

.research-card-body h3 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.4rem;
  color: #111827;
}

.research-card-body p {
  font-size: 0.87rem;
  color: #6b7280;
}

/* ── Publications ── */
.publications { background: #f9fafb; }

.pub-list { display: flex; flex-direction: column; gap: 1.75rem; }

.pub-card {
  background: #ffffff;
  border: 1px solid #e5e7eb;
  border-radius: 10px;
  padding: 1.75rem 2rem;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 1.5rem;
  align-items: start;
  transition: box-shadow 0.2s;
}

.pub-card:hover { box-shadow: 0 4px 20px rgba(0,0,0,0.07); }

.pub-badge {
  display: inline-block;
  background: #eff6ff;
  color: #1d4ed8;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 0.25rem 0.65rem;
  border-radius: 3px;
  margin-bottom: 0.65rem;
}

.pub-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: #111827;
  margin-bottom: 0.4rem;
}

.pub-authors {
  font-size: 0.82rem;
  color: #6b7280;
  margin-bottom: 0.75rem;
}

.pub-abstract {
  font-size: 0.88rem;
  color: #374151;
  margin-bottom: 1rem;
}

.pub-findings {
  background: #f0f9ff;
  border-left: 3px solid #38bdf8;
  padding: 0.75rem 1rem;
  border-radius: 0 6px 6px 0;
  font-size: 0.85rem;
  color: #0c4a6e;
}

.pub-findings strong { display: block; margin-bottom: 0.25rem; color: #0369a1; }

.pub-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.5rem 1.1rem;
  background: #1d4ed8;
  color: #fff;
  border-radius: 6px;
  font-size: 0.82rem;
  font-weight: 600;
  white-space: nowrap;
  transition: background 0.2s;
}

.pub-link:hover { background: #1e40af; }

.pub-link svg { flex-shrink: 0; }

/* ── Experience Timeline ── */
.timeline { display: flex; flex-direction: column; gap: 0; }

.timeline-item {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 0 2rem;
  padding: 1.5rem 0;
  border-bottom: 1px solid #f3f4f6;
}

.timeline-item:last-child { border-bottom: none; }

.timeline-date {
  font-size: 0.82rem;
  color: #6b7280;
  font-weight: 500;
  padding-top: 2px;
}

.timeline-date .timeline-org {
  display: block;
  font-weight: 700;
  color: #1d4ed8;
  font-size: 0.88rem;
  margin-bottom: 0.15rem;
}

.timeline-body h3 {
  font-size: 1rem;
  font-weight: 700;
  color: #111827;
  margin-bottom: 0.35rem;
}

.timeline-body ul {
  padding-left: 1.1rem;
  font-size: 0.88rem;
  color: #374151;
}

.timeline-body ul li { margin-bottom: 0.2rem; }

/* ── Skills ── */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 1.5rem;
}

.skill-group h3 {
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: #9ca3af;
  margin-bottom: 0.6rem;
}

.skill-group p {
  font-size: 0.9rem;
  color: #374151;
}

/* ── Footer ── */
.site-footer {
  background: #111827;
  color: #9ca3af;
  padding: 3rem 8%;
  text-align: center;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 3.5rem;
  margin-bottom: 2rem;
}

.footer-link {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  color: #9ca3af;
  transition: color 0.2s;
}

.footer-link:hover { color: #e5e7eb; }

.footer-link img {
  width: 36px;
  height: 36px;
  object-fit: contain;
  filter: brightness(0.7) invert(1);
  transition: filter 0.2s;
}

.footer-link:hover img { filter: brightness(1) invert(1); }

.footer-link span {
  font-size: 0.82rem;
  font-weight: 500;
  letter-spacing: 0.05em;
}

.footer-copy {
  font-size: 0.78rem;
  color: #4b5563;
  margin-top: 1.5rem;
}

/* ── Responsive ── */
@media (max-width: 768px) {
  .about-grid { grid-template-columns: 1fr; gap: 2rem; }
  .pub-card { grid-template-columns: 1fr; }
  .timeline-item { grid-template-columns: 1fr; gap: 0.25rem; }
  .footer-links { gap: 2rem; flex-wrap: wrap; }
  .section { padding: 3.5rem 5%; }
}