/* ============================================================
   ROOT VARIABLES — change --teal to any color to retheme site
   ============================================================ */
:root {
  --teal: #1D9E75;
  --teal-light: #E1F5EE;
  --teal-dark: #0F6E56;
  --text: #1a1a1a;
  --text-muted: #555555;
  --bg: #ffffff;
  --bg-soft: #f8f9f7;
  --border: #e0e0e0;
  --serif: 'Playfair Display', serif;
  --sans: 'Inter', sans-serif;
}

/* ============================================================
   RESET & BASE
   ============================================================ */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--sans);
  color: var(--text);
  background: var(--bg);
  font-size: 15px;
  line-height: 1.7;
}
h1, h2, h3 { font-family: var(--serif); }
a { color: inherit; }

/* ============================================================
   NAVIGATION
   ============================================================ */
nav {
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.97);
  border-bottom: 1px solid var(--border);
  z-index: 100;
  padding: 0 2rem;
}
.nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.nav-logo {
  font-family: var(--serif);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--teal);
  text-decoration: none;
}
.nav-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}
.nav-links a {
  text-decoration: none;
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  transition: color 0.2s;
}
.nav-links a:hover { color: var(--teal); }

/* ============================================================
   SHARED SECTION STYLES
   ============================================================ */
section { padding: 5rem 2rem; }
.container { max-width: 1100px; margin: 0 auto; }
.section-label {
  font-family: var(--sans);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--teal);
  margin-bottom: 0.5rem;
}
.section-title {
  font-family: var(--serif);
  font-size: 2rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 2rem;
}

/* ============================================================
   HERO
   ============================================================ */
#hero {
  background: var(--bg);
  padding: 7rem 2rem 5rem;
  border-bottom: 1px solid var(--border);
}
.hero-inner {
  max-width: 1100px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 4rem;
  align-items: center;
}
.hero-tag {
  display: inline-block;
  background: var(--teal-light);
  color: var(--teal-dark);
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  padding: 0.3rem 0.9rem;
  border-radius: 20px;
  margin-bottom: 1.2rem;
}
.hero-name {
  font-family: var(--serif);
  font-size: 3rem;
  font-weight: 700;
  line-height: 1.15;
  margin-bottom: 0.6rem;
  color: var(--text);
}
.hero-title {
  font-size: 1.1rem;
  color: var(--teal);
  font-weight: 500;
  margin-bottom: 1rem;
}
.hero-bio {
  color: var(--text-muted);
  font-size: 0.95rem;
  max-width: 520px;
  margin-bottom: 2rem;
  line-height: 1.8;
}
.hero-actions {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.65rem 1.4rem;
  border-radius: 6px;
  font-size: 0.88rem;
  font-weight: 500;
  text-decoration: none;
  transition: all 0.2s;
  cursor: pointer;
  border: none;
  font-family: var(--sans);
}
.btn-primary { background: var(--teal); color: #fff; }
.btn-primary:hover { background: var(--teal-dark); }
.btn-outline {
  background: transparent;
  color: var(--teal);
  border: 1.5px solid var(--teal);
}
.btn-outline:hover { background: var(--teal-light); }
.hero-links {
  display: flex;
  gap: 1.5rem;
  margin-top: 1.5rem;
}
.social-link {
  color: var(--text-muted);
  font-size: 0.85rem;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.3rem;
  transition: color 0.2s;
}
.social-link:hover { color: var(--teal); }
.hero-photo {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  background: var(--teal-light);
  border: 4px solid var(--teal);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--serif);
  font-size: 3.5rem;
  color: var(--teal);
  flex-shrink: 0;
  overflow: hidden;
}
.hero-photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* ============================================================
   ABOUT
   ============================================================ */
#about { background: var(--bg-soft); }
.about-grid {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 3rem;
  align-items: start;
}
.about-text p {
  color: var(--text-muted);
  margin-bottom: 1rem;
  font-size: 0.95rem;
}
.about-highlights {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.highlight-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.2rem;
  border-left: 3px solid var(--teal);
}
.highlight-card h4 {
  font-family: var(--serif);
  font-size: 0.95rem;
  margin-bottom: 0.25rem;
}
.highlight-card p {
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* ============================================================
   RESEARCH & PUBLICATIONS
   ============================================================ */
#research { background: var(--bg); }
.pub-list {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}
.pub-card {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.5rem;
  transition: border-color 0.2s;
}
.pub-card:hover { border-color: var(--teal); }
.pub-venue {
  display: inline-block;
  background: var(--teal-light);
  color: var(--teal-dark);
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.2rem 0.7rem;
  border-radius: 20px;
  margin-bottom: 0.6rem;
}
.pub-title {
  font-family: var(--serif);
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--text);
}
.pub-authors {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}
.pub-abstract {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 0.8rem;
}
.pub-links { display: flex; gap: 0.8rem; }
.pub-link {
  font-size: 0.82rem;
  color: var(--teal);
  text-decoration: none;
  font-weight: 500;
}
.pub-link:hover { text-decoration: underline; }

/* ============================================================
   PROJECTS
   ============================================================ */
#projects { background: var(--bg-soft); }
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}
.project-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.5rem;
  transition: border-color 0.2s;
}
.project-card:hover { border-color: var(--teal); }
.project-tag {
  display: inline-block;
  background: var(--teal-light);
  color: var(--teal-dark);
  font-size: 0.7rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: 20px;
  margin-bottom: 0.8rem;
}
.project-title {
  font-family: var(--serif);
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}
.project-desc {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 1rem;
}
.tech-tags { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.tech-tag {
  background: var(--bg-soft);
  border: 1px solid var(--border);
  font-size: 0.72rem;
  padding: 0.15rem 0.5rem;
  border-radius: 4px;
  color: var(--text-muted);
}

/* ============================================================
   EXPERIENCE TIMELINE
   ============================================================ */
#experience { background: var(--bg); }
.timeline {
  display: flex;
  flex-direction: column;
  position: relative;
}
.timeline::before {
  content: '';
  position: absolute;
  left: 8px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--border);
}
.timeline-item {
  padding-left: 2.5rem;
  padding-bottom: 2.5rem;
  position: relative;
}
.timeline-dot {
  position: absolute;
  left: 0;
  top: 6px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--teal);
  border: 3px solid var(--bg);
  z-index: 1;
}
.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: start;
  margin-bottom: 0.3rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.timeline-role {
  font-family: var(--serif);
  font-size: 1rem;
  font-weight: 600;
}
.timeline-date {
  font-size: 0.8rem;
  color: var(--teal);
  font-weight: 500;
  white-space: nowrap;
}
.timeline-company {
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 0.6rem;
}
.timeline-bullets {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}
.timeline-bullets li {
  font-size: 0.85rem;
  color: var(--text-muted);
  padding-left: 1rem;
  position: relative;
}
.timeline-bullets li::before {
  content: '▸';
  position: absolute;
  left: 0;
  color: var(--teal);
  font-size: 0.7rem;
  top: 3px;
}

/* ============================================================
   TEACHING
   ============================================================ */
#teaching { background: var(--bg-soft); }
.teaching-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.2rem;
}
.teaching-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.2rem;
  border-top: 3px solid var(--teal);
}
.teaching-course {
  font-family: var(--serif);
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0.3rem;
}
.teaching-meta {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ============================================================
   SERVICE & VOLUNTEERING
   ============================================================ */
#service { background: var(--bg); }
.service-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.service-item {
  display: flex;
  gap: 1.5rem;
  align-items: start;
  padding: 1.2rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  transition: border-color 0.2s;
}
.service-item:hover { border-color: var(--teal); }
.service-icon {
  width: 40px;
  height: 40px;
  border-radius: 8px;
  background: var(--teal-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.1rem;
  flex-shrink: 0;
  color: var(--teal);
}
.service-title {
  font-family: var(--serif);
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
}
.service-meta {
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* ============================================================
   SKILLS
   ============================================================ */
#skills { background: var(--bg-soft); }
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
}
.skill-group {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.2rem;
}
.skill-group-title {
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--teal);
  margin-bottom: 0.8rem;
}
.skill-tags { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.skill-tag {
  background: var(--teal-light);
  color: var(--teal-dark);
  font-size: 0.78rem;
  padding: 0.25rem 0.6rem;
  border-radius: 20px;
  font-weight: 500;
}

/* ============================================================
   EDUCATION
   ============================================================ */
#education { background: var(--bg); }
.edu-list {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
}
.edu-card {
  display: flex;
  gap: 1.5rem;
  align-items: start;
  padding: 1.5rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  transition: border-color 0.2s;
}
.edu-card:hover { border-color: var(--teal); }
.edu-icon {
  width: 48px;
  height: 48px;
  border-radius: 8px;
  background: var(--teal-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--serif);
  font-weight: 700;
  color: var(--teal);
  flex-shrink: 0;
  font-size: 0.85rem;
}
.edu-degree {
  font-family: var(--serif);
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.2rem;
}
.edu-school {
  font-size: 0.88rem;
  color: var(--teal);
  font-weight: 500;
  margin-bottom: 0.2rem;
}
.edu-meta {
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* ============================================================
   CONTACT
   ============================================================ */
#contact { background: var(--bg-soft); text-align: center; }
.contact-inner { max-width: 600px; margin: 0 auto; }
.contact-desc {
  color: var(--text-muted);
  margin-bottom: 2.5rem;
  font-size: 0.95rem;
}
.contact-links {
  display: flex;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
}
.contact-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.4rem;
  text-decoration: none;
  color: var(--text-muted);
  font-size: 0.85rem;
  transition: color 0.2s;
}
.contact-item:hover { color: var(--teal); }
.contact-icon {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--bg);
  border: 1.5px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  font-weight: 600;
  transition: border-color 0.2s, background 0.2s;
}
.contact-item:hover .contact-icon {
  border-color: var(--teal);
  background: var(--teal-light);
  color: var(--teal);
}

/* ============================================================
   FOOTER
   ============================================================ */
footer {
  background: #1a1a1a;
  color: #aaa;
  text-align: center;
  padding: 2rem;
  font-size: 0.82rem;
}
footer span { color: var(--teal); }

/* ============================================================
   RESPONSIVE — basic mobile support
   ============================================================ */
@media (max-width: 768px) {
  .hero-inner { grid-template-columns: 1fr; }
  .hero-photo { width: 140px; height: 140px; font-size: 2.5rem; order: -1; }
  .hero-name { font-size: 2.2rem; }
  .about-grid { grid-template-columns: 1fr; }
  .nav-links { display: none; }
}