:root {
  --accent: #0891b2;
  --accent-hover: #0e7490;
  --accent-light: #ecfeff;
  --accent-btn: #0e7490;
  --gradient-1: #0891b2;
  --gradient-2: #06b6d4;
}

[data-theme="light"] {
  --bg: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --text: #1e293b;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --border: #e2e8f0;
  --card-bg: #ffffff;
  --shadow: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-lg: 0 4px 12px rgba(0,0,0,0.1);
}

[data-theme="dark"] {
  --bg: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --text: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --border: #334155;
  --card-bg: #1e293b;
  --shadow: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-lg: 0 4px 12px rgba(0,0,0,0.4);
  --accent: #22d3ee;
  --accent-hover: #06b6d4;
  --accent-light: #0f2937;
  --accent-btn: #0891b2;
}

*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  transition: background 0.3s ease, color 0.3s ease;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  color: var(--accent-hover);
}

img {
  max-width: 100%;
  height: auto;
}

.container {
  width: 100%;
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header / Nav */
.site-header {
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  position: sticky;
  top: 0;
  z-index: 100;
  transition: background 0.3s;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.main-nav {
  display: flex;
  gap: 32px;
}

.main-nav a {
  color: var(--text-secondary);
  font-size: 0.9rem;
  font-weight: 500;
  position: relative;
}

.main-nav a:hover,
.main-nav a[aria-current="page"] {
  color: var(--accent);
}

.main-nav a[aria-current="page"]::after {
  content: "";
  position: absolute;
  bottom: -20px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent);
  border-radius: 1px;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text);
  font-size: 1.5rem;
  cursor: pointer;
  padding: 4px;
}

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  width: 36px;
  height: 36px;
  cursor: pointer;
  color: var(--text);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s, border-color 0.2s;
}

.theme-toggle svg {
  display: block;
}

.theme-toggle:hover {
  background: var(--bg-secondary);
  border-color: var(--accent);
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 32px 0;
  background: var(--bg-secondary);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-inner p {
  color: var(--text-muted);
  font-size: 0.85rem;
}

.social-links {
  display: flex;
  gap: 20px;
}

.social-links a {
  color: var(--text-muted);
  font-size: 0.85rem;
}

.social-links a:hover {
  color: var(--accent);
}

/* Hero */
.hero {
  flex: 1;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -50%;
  right: -30%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, var(--accent-light) 0%, transparent 70%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero-greeting {
  font-size: 1rem;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 12px;
  display: block;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.03em;
  margin-bottom: 16px;
  color: var(--text);
}

.hero h1 span {
  background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 540px;
  margin-bottom: 32px;
  line-height: 1.7;
}

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

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  border: none;
}

.btn-primary {
  background: var(--accent-btn);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent-hover);
  color: #fff;
}

.btn-secondary {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* Page header */
.page-header {
  padding: 64px 0 48px;
}

.page-header h1 {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}

.page-header p {
  color: var(--text-secondary);
  font-size: 1.1rem;
  max-width: 560px;
}

/* About */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  padding-bottom: 80px;
}

.about-text p {
  color: var(--text-secondary);
  margin-bottom: 20px;
  font-size: 1.05rem;
  line-height: 1.8;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.stat-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  text-align: center;
  box-shadow: var(--shadow);
}

.stat-number {
  font-size: 2rem;
  font-weight: 800;
  color: var(--accent);
  line-height: 1;
  margin-bottom: 6px;
}

.stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.about-education {
  margin-top: 24px;
  padding: 20px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow);
}

.about-education h3 {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.edu-item {
  margin-bottom: 12px;
}

.edu-item:last-child {
  margin-bottom: 0;
}

.edu-item .school {
  font-weight: 600;
  color: var(--text);
}

.edu-item .degree {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.edu-item .year {
  color: var(--text-muted);
  font-size: 0.8rem;
}

.resume-download {
  margin-top: 24px;
}

/* Timeline */
.timeline {
  position: relative;
  padding-bottom: 80px;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 24px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--border);
}

.timeline-item {
  position: relative;
  padding-left: 64px;
  padding-bottom: 48px;
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-dot {
  position: absolute;
  left: 17px;
  top: 4px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--accent);
  border: 3px solid var(--bg);
  box-shadow: 0 0 0 2px var(--accent);
}

.timeline-date {
  font-size: 0.8rem;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 4px;
}

.timeline-title {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.timeline-company {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 16px;
}

.timeline-details {
  list-style: none;
}

.timeline-details li {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 8px;
  padding-left: 20px;
  position: relative;
  line-height: 1.6;
}

.timeline-details li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--text-muted);
}

/* Skills */
.skills-section {
  padding-bottom: 64px;
}

.skills-section h2 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 24px;
}

.skill-category {
  margin-bottom: 32px;
}

.skill-category-title {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  font-weight: 600;
  margin-bottom: 12px;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.skill-tag {
  display: inline-block;
  padding: 6px 14px;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
  border: 1px solid transparent;
  transition: all 0.2s;
}

.skill-tag:hover {
  border-color: var(--accent);
  transform: translateY(-1px);
}

/* Projects */
.projects-section {
  padding-bottom: 80px;
}

.projects-section h2 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 24px;
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 24px;
}

.project-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 24px;
  box-shadow: var(--shadow);
  transition: box-shadow 0.2s, transform 0.2s;
}

.project-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.project-card-title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--text);
}

.project-card-desc {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.6;
  margin-bottom: 16px;
}

.project-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 16px;
}

.project-card-tag {
  font-size: 0.75rem;
  padding: 3px 10px;
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  border-radius: 12px;
}

.project-card-link {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--accent);
}

.project-card-link:hover {
  color: var(--accent-hover);
}

/* Section spacing */
.section-divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: 0 0 48px;
}

/* Mobile */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2.2rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }

  .page-header h1 {
    font-size: 1.8rem;
  }

  .page-header {
    padding: 40px 0 32px;
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .stats-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
  }

  .stat-card {
    padding: 16px;
  }

  .stat-number {
    font-size: 1.5rem;
  }

  .nav-toggle {
    display: block;
  }

  .main-nav {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    padding: 16px 24px;
    gap: 0;
  }

  .main-nav.open {
    display: flex;
  }

  .main-nav a {
    padding: 12px 0;
    border-bottom: 1px solid var(--border);
  }

  .main-nav a:last-child {
    border-bottom: none;
  }

  .main-nav a[aria-current="page"]::after {
    display: none;
  }

  .projects-grid {
    grid-template-columns: 1fr;
  }

  .timeline-item {
    padding-left: 48px;
  }

  .timeline::before {
    left: 16px;
  }

  .timeline-dot {
    left: 9px;
  }

  .footer-inner {
    flex-direction: column;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.8rem;
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }

  .hero-actions {
    flex-direction: column;
  }

  .btn {
    width: 100%;
    justify-content: center;
  }
}