/* ============================================================
   Yu-Cheng Tsai — Personal Website Styles
   ============================================================ */

:root {
  --bg: #060d1f;
  --bg-surface: #0c1628;
  --bg-card: #111e33;
  --bg-card-hover: #162540;
  --border: #1e3352;
  --border-light: #243d63;

  --text-primary: #f0f4ff;
  --text-secondary: #8da4c4;
  --text-muted: #4d6a8f;

  --accent-blue: #3b82f6;
  --accent-purple: #8b5cf6;
  --accent-cyan: #06b6d4;
  --accent-green: #10b981;

  --gradient: linear-gradient(135deg, #3b82f6, #8b5cf6);
  --gradient-text: linear-gradient(135deg, #60a5fa, #a78bfa, #67e8f9);

  --nav-h: 68px;
  --radius: 12px;
  --radius-lg: 20px;
  --radius-sm: 8px;

  --shadow: 0 4px 24px rgba(0,0,0,0.4);
  --shadow-lg: 0 12px 48px rgba(0,0,0,0.6);
  --shadow-glow: 0 0 40px rgba(59,130,246,0.15);

  --transition: 0.2s ease;
  --transition-slow: 0.4s ease;
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
ul { list-style: none; }
img { max-width: 100%; display: block; }

/* ── Typography ── */
h1, h2, h3, h4 { font-weight: 700; line-height: 1.2; letter-spacing: -0.02em; }
h1 { font-size: clamp(2.4rem, 6vw, 4.2rem); }
h2 { font-size: clamp(1.8rem, 4vw, 2.8rem); }
h3 { font-size: 1.25rem; font-weight: 600; }
h4 { font-size: 1.05rem; font-weight: 600; }
p { color: var(--text-secondary); line-height: 1.75; }

/* ── Navigation ── */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  height: var(--nav-h);
  background: rgba(6, 13, 31, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition), background var(--transition);
}
.nav.scrolled {
  border-bottom-color: var(--border);
  background: rgba(6, 13, 31, 0.96);
}
.nav-container {
  max-width: 1200px; margin: 0 auto;
  height: 100%;
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 24px;
}
.nav-logo {
  font-size: 1.25rem; font-weight: 800; letter-spacing: -0.03em;
  color: var(--text-primary);
}
.nav-logo .accent { color: var(--accent-blue); }
.nav-links {
  display: flex; align-items: center; gap: 32px;
}
.nav-links a {
  font-size: 0.875rem; font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition);
}
.nav-links a:hover { color: var(--text-primary); }
.nav-cta {
  background: var(--gradient) !important;
  color: #fff !important;
  padding: 8px 20px;
  border-radius: 100px;
  font-weight: 600 !important;
  transition: opacity var(--transition) !important;
}
.nav-cta:hover { opacity: 0.85; }

.hamburger {
  display: none;
  flex-direction: column; gap: 5px;
  background: none; border: none; cursor: pointer; padding: 4px;
}
.hamburger span {
  display: block; width: 22px; height: 2px;
  background: var(--text-secondary); border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}
.hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Mobile Menu */
.mobile-menu {
  position: fixed; top: var(--nav-h); left: 0; right: 0; z-index: 99;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border);
  display: flex; flex-direction: column;
  padding: 16px 24px 24px;
  transform: translateY(-110%);
  transition: transform var(--transition-slow);
  gap: 4px;
}
.mobile-menu.open { transform: translateY(0); }
.mobile-link {
  font-size: 1rem; font-weight: 500;
  color: var(--text-secondary);
  padding: 12px 0;
  border-bottom: 1px solid var(--border);
  transition: color var(--transition);
}
.mobile-link:last-child { border-bottom: none; }
.mobile-link:hover { color: var(--text-primary); }

/* ── Hero ── */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex; align-items: center; justify-content: center;
  padding: calc(var(--nav-h) + 60px) 24px 80px;
  overflow: hidden;
  text-align: center;
}

.hero-bg {
  position: absolute; inset: 0; z-index: 0;
  background: radial-gradient(ellipse 80% 60% at 50% 0%, rgba(59,130,246,0.12) 0%, transparent 70%),
              radial-gradient(ellipse 60% 40% at 80% 80%, rgba(139,92,246,0.08) 0%, transparent 60%);
}
.grid-overlay {
  position: absolute; inset: 0;
  background-image:
    linear-gradient(rgba(59,130,246,0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(59,130,246,0.04) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse 80% 80% at 50% 0%, black 30%, transparent 100%);
}
.orb {
  position: absolute; border-radius: 50%;
  filter: blur(80px); pointer-events: none;
}
.orb-1 {
  width: 600px; height: 600px;
  background: radial-gradient(circle, rgba(59,130,246,0.18) 0%, transparent 70%);
  top: -200px; left: 50%; transform: translateX(-50%);
}
.orb-2 {
  width: 400px; height: 400px;
  background: radial-gradient(circle, rgba(139,92,246,0.12) 0%, transparent 70%);
  bottom: 0; right: -100px;
}
.orb-3 {
  width: 300px; height: 300px;
  background: radial-gradient(circle, rgba(6,182,212,0.08) 0%, transparent 70%);
  bottom: 100px; left: -50px;
}

.hero-content {
  position: relative; z-index: 1;
  max-width: 820px; margin: 0 auto;
  display: flex; flex-direction: column; align-items: center; gap: 24px;
}

.hero-avatar {
  width: 120px; height: 120px;
  border-radius: 50%;
  overflow: hidden;
  border: 3px solid rgba(59,130,246,0.4);
  box-shadow: 0 0 0 6px rgba(59,130,246,0.08), var(--shadow-glow);
  flex-shrink: 0;
}
.hero-avatar img {
  width: 100%; height: 100%;
  object-fit: cover;
  object-position: center 20%;
  transform: scale(1.1);
  transform-origin: center top;
}

.hero-badge {
  display: inline-flex; align-items: center; gap: 10px;
  background: rgba(59,130,246,0.1);
  border: 1px solid rgba(59,130,246,0.25);
  border-radius: 100px;
  padding: 8px 20px;
  font-size: 0.8rem; font-weight: 500;
  color: #93c5fd;
  letter-spacing: 0.02em;
}
.badge-dot {
  width: 7px; height: 7px; border-radius: 50%;
  background: var(--accent-green);
  box-shadow: 0 0 8px var(--accent-green);
  animation: pulse 2s infinite;
}
@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.6; transform: scale(0.85); }
}

.hero-name { color: var(--text-primary); }
.hero-phd { font-size: 1em; color: var(--text-primary); font-weight: 700; }

.hero-tagline {
  font-size: clamp(1.1rem, 2.5vw, 1.4rem);
  font-weight: 400;
  color: var(--text-secondary);
  line-height: 1.5;
}
.gradient-text {
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-weight: 700;
}

.hero-description {
  max-width: 620px;
  font-size: 1rem;
  color: var(--text-secondary);
}

.hero-actions {
  display: flex; gap: 16px; flex-wrap: wrap; justify-content: center;
}

.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 13px 28px; border-radius: 100px;
  font-size: 0.925rem; font-weight: 600;
  transition: all var(--transition); cursor: pointer; border: none;
}
.btn-primary {
  background: var(--gradient);
  color: #fff;
  box-shadow: 0 4px 20px rgba(59,130,246,0.35);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 32px rgba(59,130,246,0.45);
}
.btn-secondary {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-light);
}
.btn-secondary:hover {
  background: var(--bg-card);
  border-color: var(--accent-blue);
  transform: translateY(-2px);
}

.hero-social {
  display: flex; gap: 16px; justify-content: center;
}
.hero-social a {
  display: flex; align-items: center; justify-content: center;
  width: 40px; height: 40px; border-radius: 10px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  transition: all var(--transition);
}
.hero-social a:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-blue);
  color: var(--text-primary);
  transform: translateY(-2px);
}

.scroll-indicator {
  position: absolute; bottom: 32px; left: 50%;
  transform: translateX(-50%);
  display: flex; flex-direction: column; align-items: center; gap: 8px;
  color: var(--text-muted); font-size: 0.7rem; letter-spacing: 0.15em; text-transform: uppercase;
}
.scroll-line {
  width: 1px; height: 40px;
  background: linear-gradient(to bottom, var(--accent-blue), transparent);
  animation: scrollLine 1.8s ease-in-out infinite;
}
@keyframes scrollLine {
  0% { transform: scaleY(0); transform-origin: top; }
  50% { transform: scaleY(1); transform-origin: top; }
  51% { transform: scaleY(1); transform-origin: bottom; }
  100% { transform: scaleY(0); transform-origin: bottom; }
}

/* ── Sections ── */
.section { padding: 100px 24px; }
.section-dark { background: var(--bg-surface); }

.container { max-width: 1100px; margin: 0 auto; }

.section-header {
  text-align: center;
  margin-bottom: 64px;
  display: flex; flex-direction: column; align-items: center; gap: 16px;
}
.section-label {
  font-size: 0.75rem; font-weight: 600;
  letter-spacing: 0.15em; text-transform: uppercase;
  color: var(--accent-blue);
}
.section-title { color: var(--text-primary); }
.section-subtitle {
  max-width: 600px;
  font-size: 1rem;
  color: var(--text-secondary);
  text-align: center;
}

/* ── About ── */
.about-grid {
  display: grid; grid-template-columns: 1fr 280px; gap: 64px; align-items: start;
}
.about-text { display: flex; flex-direction: column; gap: 20px; }
.about-text p { font-size: 1.05rem; }
.about-text strong { color: var(--text-primary); font-weight: 600; }

.about-stats {
  display: grid; grid-template-columns: 1fr 1fr; gap: 16px;
}
.stat-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 16px;
  text-align: center;
  transition: border-color var(--transition), transform var(--transition);
}
.stat-card:hover {
  border-color: var(--accent-blue);
  transform: translateY(-3px);
}
.stat-number {
  font-size: 1.8rem; font-weight: 800;
  background: var(--gradient-text);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1; margin-bottom: 8px;
}
.stat-label { font-size: 0.75rem; color: var(--text-muted); font-weight: 500; }

/* ── Patents ── */
.patents-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px;
}

.patent-card-full {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: all var(--transition);
  display: flex; flex-direction: column; gap: 14px;
}
.patent-card-full:hover {
  border-color: var(--accent-blue);
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
}
.patent-link { cursor: pointer; text-decoration: none; }
.patent-link:hover { border-color: var(--accent-blue); transform: translateY(-4px); box-shadow: var(--shadow-glow); }

.patent-view {
  font-size: 0.8rem; font-weight: 600;
  color: var(--accent-blue);
  margin-top: auto;
}

.patent-header {
  display: flex; align-items: center; gap: 12px;
}
.patent-icon { font-size: 1.5rem; }
.patent-id-wrap { display: flex; flex-direction: column; gap: 4px; }
.patent-id {
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.8rem; font-weight: 500;
  color: var(--accent-cyan);
}
.patent-status {
  display: inline-block;
  font-size: 0.68rem; font-weight: 600;
  letter-spacing: 0.08em; text-transform: uppercase;
  padding: 2px 8px; border-radius: 100px;
}
.status-granted { background: rgba(16,185,129,0.15); color: #34d399; }
.status-pending { background: rgba(59,130,246,0.15); color: #93c5fd; }

.patent-card-full h3 { color: var(--text-primary); font-size: 1.05rem; }
.patent-card-full p { font-size: 0.9rem; flex: 1; }

.patent-tags {
  display: flex; flex-wrap: wrap; gap: 6px; margin-top: 4px;
}
.patent-tags span {
  font-size: 0.72rem; font-weight: 500;
  padding: 3px 10px; border-radius: 100px;
  background: rgba(59,130,246,0.1);
  border: 1px solid rgba(59,130,246,0.2);
  color: #93c5fd;
}

/* ── Timeline ── */
.timeline { position: relative; max-width: 800px; margin: 0 auto; }
.timeline::before {
  content: '';
  position: absolute; left: 16px; top: 0; bottom: 0;
  width: 1px; background: var(--border);
}

.timeline-item {
  position: relative;
  padding-left: 56px;
  margin-bottom: 48px;
}
.timeline-item:last-child { margin-bottom: 0; }

.timeline-marker {
  position: absolute; left: 0; top: 4px;
  width: 33px; height: 33px; border-radius: 50%;
  background: var(--bg-card);
  border: 2px solid var(--border-light);
  display: flex; align-items: center; justify-content: center;
}
.timeline-marker.current {
  border-color: var(--accent-blue);
  background: rgba(59,130,246,0.15);
  box-shadow: 0 0 20px rgba(59,130,246,0.25);
}
.timeline-marker.current::after {
  content: '';
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--accent-blue);
}
.timeline-marker::after {
  content: '';
  width: 8px; height: 8px; border-radius: 50%;
  background: var(--border-light);
}
.timeline-marker.edu { border-color: var(--accent-purple); }
.timeline-marker.edu::after { background: var(--accent-purple); }

.timeline-content {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: border-color var(--transition);
}
.timeline-content:hover { border-color: var(--border-light); }

.timeline-header {
  display: flex; justify-content: space-between; align-items: flex-start;
  gap: 16px; margin-bottom: 12px;
}
.timeline-header h3 { color: var(--text-primary); font-size: 1.05rem; }
.timeline-company { font-size: 0.875rem; color: var(--accent-blue); font-weight: 500; margin-top: 4px; }
.timeline-badge {
  flex-shrink: 0;
  font-size: 0.72rem; font-weight: 600;
  padding: 3px 12px; border-radius: 100px;
  background: rgba(16,185,129,0.15);
  color: #34d399;
  white-space: nowrap;
}

.timeline-bullets {
  display: flex; flex-direction: column; gap: 8px;
  margin-bottom: 16px;
}
.timeline-bullets li {
  font-size: 0.9rem; color: var(--text-secondary);
  padding-left: 16px; position: relative;
}
.timeline-bullets li::before {
  content: '→';
  position: absolute; left: 0;
  color: var(--accent-blue); font-size: 0.8rem;
}
.timeline-bullets li strong { color: var(--text-primary); }
.timeline-desc { font-size: 0.9rem; color: var(--text-secondary); margin-bottom: 16px; }

.timeline-tags {
  display: flex; flex-wrap: wrap; gap: 6px;
}
.timeline-tags span {
  font-size: 0.72rem; font-weight: 500;
  padding: 3px 10px; border-radius: 100px;
  background: rgba(139,92,246,0.1);
  border: 1px solid rgba(139,92,246,0.2);
  color: #c4b5fd;
}

/* ── Publications ── */
.pub-featured-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 20px;
  margin-bottom: 32px;
}
.pub-featured-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  display: flex; flex-direction: column; gap: 12px;
  transition: all var(--transition);
  cursor: pointer;
}
.pub-featured-card:hover {
  border-color: var(--accent-blue);
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
}
.pub-featured-label {
  font-size: 0.72rem; font-weight: 600;
  letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--accent-blue);
}
.pub-featured-card h3 {
  color: var(--text-primary); font-size: 1.05rem; line-height: 1.4;
}
.pub-featured-card p { font-size: 0.88rem; flex: 1; }
.pub-featured-source { font-size: 0.78rem; color: var(--text-muted); }
.pub-featured-arrow {
  font-size: 0.85rem; font-weight: 600;
  color: var(--accent-blue);
  margin-top: auto;
}

.pub-list { display: flex; flex-direction: column; gap: 0; margin-bottom: 32px; }
.pub-item {
  display: flex; align-items: center; justify-content: space-between; gap: 20px;
  padding: 24px 0;
  border-bottom: 1px solid var(--border);
  transition: all var(--transition);
  cursor: pointer;
}
.pub-item:first-child { border-top: 1px solid var(--border); }
.pub-item:hover .pub-arrow { color: var(--accent-blue); transform: translateX(4px); }
.pub-item:hover h4 { color: var(--accent-blue); }

.pub-left { display: flex; flex-direction: column; gap: 8px; flex: 1; }
.pub-tag {
  display: inline-block;
  font-size: 0.68rem; font-weight: 600;
  letter-spacing: 0.08em; text-transform: uppercase;
  padding: 2px 10px; border-radius: 100px;
  width: fit-content;
}
.pub-tag-agent { background: rgba(59,130,246,0.15); color: #93c5fd; }
.pub-tag-llm { background: rgba(139,92,246,0.15); color: #c4b5fd; }

.pub-item h4 { color: var(--text-primary); transition: color var(--transition); }
.pub-item p { font-size: 0.875rem; }
.pub-source { font-size: 0.78rem; color: var(--text-muted); }

.pub-arrow {
  font-size: 1.2rem; color: var(--text-muted);
  transition: all var(--transition); flex-shrink: 0;
}

.tech-good-box {
  display: flex; align-items: flex-start; gap: 20px;
  background: linear-gradient(135deg, rgba(16,185,129,0.08), rgba(6,182,212,0.05));
  border: 1px solid rgba(16,185,129,0.2);
  border-radius: var(--radius);
  padding: 24px 28px;
  margin-bottom: 32px;
}
.tech-good-icon { font-size: 1.8rem; flex-shrink: 0; }
.tech-good-box h4 { color: #34d399; margin-bottom: 6px; }
.tech-good-box p { font-size: 0.9rem; }

.pub-more { text-align: center; }

/* ── Tech for Good ── */
.tech-good-section {
  background: linear-gradient(135deg, rgba(16,185,129,0.06), rgba(6,182,212,0.04));
  border: 1px solid rgba(16,185,129,0.18);
  border-radius: var(--radius-lg);
  padding: 36px;
  margin-bottom: 36px;
}
.tech-good-header { margin-bottom: 28px; }
.tech-good-title-row {
  display: flex; align-items: flex-start; gap: 16px;
}
.tech-good-emoji { font-size: 2rem; flex-shrink: 0; margin-top: 2px; }
.tech-good-heading {
  font-size: 1.2rem; font-weight: 700;
  color: #34d399; margin-bottom: 6px;
}
.tech-good-intro { font-size: 0.9rem; color: var(--text-secondary); }

.tech-good-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 20px;
}
.tech-good-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  display: flex; flex-direction: column; gap: 14px;
  transition: all var(--transition);
  cursor: pointer;
}
.tech-good-card:hover {
  border-color: #34d399;
  transform: translateY(-3px);
  box-shadow: 0 0 30px rgba(16,185,129,0.1);
}
.tgc-top {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
}
.tgc-badge {
  font-size: 0.68rem; font-weight: 600;
  letter-spacing: 0.08em; text-transform: uppercase;
  padding: 2px 10px; border-radius: 100px;
  background: rgba(16,185,129,0.15); color: #34d399;
}
.tgc-partner {
  font-size: 0.75rem; color: var(--text-muted);
}
.tech-good-card h4 { color: var(--text-primary); font-size: 1rem; line-height: 1.4; }
.tgc-problem { font-size: 0.875rem; }
.tgc-problem strong { color: var(--text-primary); }

.tgc-built { display: flex; flex-direction: column; gap: 8px; }
.tgc-built-label {
  font-size: 0.72rem; font-weight: 600;
  letter-spacing: 0.08em; text-transform: uppercase;
  color: var(--accent-cyan);
}
.tgc-built ul { display: flex; flex-direction: column; gap: 6px; }
.tgc-built li {
  font-size: 0.85rem; color: var(--text-secondary);
  padding-left: 14px; position: relative;
}
.tgc-built li::before {
  content: '▸';
  position: absolute; left: 0;
  color: #34d399; font-size: 0.7rem; top: 2px;
}
.tgc-built li strong { color: var(--text-primary); }

.tgc-tags {
  display: flex; flex-wrap: wrap; gap: 6px; margin-top: 4px;
}
.tgc-tags span {
  font-size: 0.7rem; font-weight: 500;
  padding: 3px 9px; border-radius: 100px;
  background: rgba(16,185,129,0.1);
  border: 1px solid rgba(16,185,129,0.2);
  color: #6ee7b7;
}
.tgc-link {
  font-size: 0.85rem; font-weight: 600;
  color: #34d399; margin-top: auto;
}

@media (max-width: 720px) {
  .tech-good-grid { grid-template-columns: 1fr; }
  .tech-good-section { padding: 24px; }
}

/* ── Teaching ── */
.teaching-card {
  display: flex; align-items: flex-start; justify-content: space-between; gap: 32px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px;
  transition: all var(--transition);
  cursor: pointer;
  max-width: 860px; margin: 0 auto;
}
.teaching-card:hover {
  border-color: var(--accent-blue);
  transform: translateY(-4px);
  box-shadow: var(--shadow-glow);
}
.teaching-card-left { display: flex; flex-direction: column; gap: 14px; flex: 1; }
.teaching-org { display: flex; align-items: center; gap: 12px; }
.teaching-badge {
  font-size: 0.68rem; font-weight: 600;
  letter-spacing: 0.08em; text-transform: uppercase;
  padding: 3px 10px; border-radius: 100px;
  background: rgba(59,130,246,0.15); color: #93c5fd;
}
.teaching-platform { font-size: 0.85rem; font-weight: 600; color: var(--accent-cyan); }
.teaching-card h3 { color: var(--text-primary); font-size: 1.15rem; }
.teaching-card p { font-size: 0.9rem; }
.teaching-tags { display: flex; flex-wrap: wrap; gap: 6px; }
.teaching-tags span {
  font-size: 0.72rem; font-weight: 500;
  padding: 3px 10px; border-radius: 100px;
  background: rgba(59,130,246,0.1);
  border: 1px solid rgba(59,130,246,0.2);
  color: #93c5fd;
}
.teaching-card-right {
  display: flex; flex-direction: column; align-items: flex-end;
  justify-content: space-between; gap: 24px; flex-shrink: 0;
}
.teaching-rating { display: flex; flex-direction: column; align-items: center; gap: 4px; }
.teaching-stars { color: #fbbf24; font-size: 1rem; letter-spacing: 2px; }
.teaching-score { font-size: 1.5rem; font-weight: 800; color: var(--text-primary); }
.teaching-link { font-size: 0.85rem; font-weight: 600; color: var(--accent-blue); white-space: nowrap; }

@media (max-width: 600px) {
  .teaching-card { flex-direction: column; }
  .teaching-card-right { flex-direction: row; align-items: center; width: 100%; }
}

/* ── Skills ── */
.skills-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 28px;
}
.skill-group {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  transition: border-color var(--transition);
}
.skill-group:hover { border-color: var(--border-light); }

.skill-group-title {
  display: flex; align-items: center; gap: 10px;
  font-size: 0.95rem; font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 16px;
}
.skill-icon { font-size: 1.1rem; }

.skill-pills { display: flex; flex-wrap: wrap; gap: 8px; }
.skill-pill {
  font-size: 0.78rem; font-weight: 500;
  padding: 5px 12px; border-radius: 100px;
  background: rgba(255,255,255,0.04);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  transition: all var(--transition);
}
.skill-pill:hover {
  border-color: var(--accent-blue);
  color: var(--text-primary);
}
.pill-primary {
  background: rgba(59,130,246,0.1);
  border-color: rgba(59,130,246,0.25);
  color: #93c5fd;
}
.pill-primary:hover { background: rgba(59,130,246,0.2); }

/* ── Contact ── */
.contact-section { padding-bottom: 120px; }
.contact-content { max-width: 760px; margin: 0 auto; }

.contact-links {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 16px;
}
.contact-card {
  display: flex; align-items: center; gap: 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  transition: all var(--transition);
}
.contact-card:hover {
  border-color: var(--accent-blue);
  transform: translateY(-3px);
  box-shadow: var(--shadow-glow);
}
.contact-card-icon {
  width: 44px; height: 44px; border-radius: 10px;
  background: rgba(59,130,246,0.1);
  border: 1px solid rgba(59,130,246,0.2);
  display: flex; align-items: center; justify-content: center;
  color: var(--accent-blue); flex-shrink: 0;
}
.contact-card-title { font-size: 0.9rem; font-weight: 600; color: var(--text-primary); }
.contact-card-sub { font-size: 0.78rem; color: var(--text-muted); margin-top: 2px; }

/* ── Footer ── */
.footer {
  background: var(--bg);
  border-top: 1px solid var(--border);
  padding: 28px 24px;
}
.footer-content {
  max-width: 1100px; margin: 0 auto;
  display: flex; justify-content: space-between; align-items: center;
  gap: 16px; flex-wrap: wrap;
}
.footer-logo { font-weight: 700; font-size: 0.95rem; color: var(--text-primary); }
.footer-copy { font-size: 0.78rem; color: var(--text-muted); }

/* ── Reveal animations ── */
.reveal {
  opacity: 0; transform: translateY(28px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.visible { opacity: 1; transform: translateY(0); }

/* ── Responsive ── */
@media (max-width: 900px) {
  .about-grid { grid-template-columns: 1fr; }
  .about-stats { grid-template-columns: repeat(4, 1fr); }
  .patents-grid { grid-template-columns: 1fr; }
  .pub-featured-grid { grid-template-columns: 1fr; }
  .skills-grid { grid-template-columns: 1fr; }
  .contact-links { grid-template-columns: 1fr; }
}

@media (max-width: 720px) {
  .nav-links { display: none; }
  .hamburger { display: flex; }
  .section { padding: 72px 20px; }
  .hero { padding-top: calc(var(--nav-h) + 40px); }
  .about-stats { grid-template-columns: repeat(2, 1fr); }
  .timeline::before { left: 12px; }
  .timeline-item { padding-left: 44px; }
  .timeline-marker { width: 25px; height: 25px; }
  .timeline-header { flex-direction: column; gap: 8px; }
  .hero-actions { flex-direction: column; align-items: center; }
  .footer-content { flex-direction: column; text-align: center; }
}

@media (max-width: 480px) {
  .stat-card { padding: 18px 12px; }
  .stat-number { font-size: 1.5rem; }
  .contact-card { padding: 16px; }
  .pub-item { flex-direction: column; align-items: flex-start; }
  .pub-arrow { display: none; }
}