:root {
  --bg-primary: #0f172a;
  --bg-surface: #1e293b;
  --bg-surface-hover: #334155;
  --border-color: #334155;
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --accent-primary: #38bdf8;
  --accent-secondary: #818cf8;
  --accent-gradient: linear-gradient(135deg, #38bdf8 0%, #818cf8 100%);
  --tag-bg: rgba(56, 189, 248, 0.1);
  --tag-text: #38bdf8;
  --card-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.3);
  --radius-lg: 16px;
  --radius-md: 10px;
  --radius-sm: 6px;
  --font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
}

[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-surface: #ffffff;
  --bg-surface-hover: #f1f5f9;
  --border-color: #e2e8f0;
  --text-primary: #0f172a;
  --text-secondary: #64748b;
  --accent-primary: #0284c7;
  --accent-secondary: #4f46e5;
  --accent-gradient: linear-gradient(135deg, #0284c7 0%, #4f46e5 100%);
  --tag-bg: rgba(2, 132, 199, 0.08);
  --tag-text: #0284c7;
  --card-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.05);
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background-color 0.3s ease, color 0.3s ease;
  min-height: 100vh;
}

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header & Nav */
header.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(15, 23, 42, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0;
  transition: background-color 0.3s ease;
}

[data-theme="light"] header.site-header {
  background-color: rgba(248, 250, 252, 0.85);
}

.nav-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  text-decoration: none;
}

.nav-controls {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.btn-toggle {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.5rem 0.9rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  transition: all 0.2s ease;
}

.btn-toggle:hover {
  background: var(--bg-surface-hover);
  border-color: var(--accent-primary);
}

/* Hero Section */
.hero {
  padding: 4rem 0 3rem;
  text-align: center;
}

.hero-avatar {
  width: 96px;
  height: 96px;
  border-radius: 50%;
  margin: 0 auto 1.25rem;
  background: var(--accent-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.25rem;
  font-weight: 700;
  color: #fff;
  box-shadow: 0 0 30px rgba(56, 189, 248, 0.3);
}

.hero h1 {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 0.5rem;
}

.hero .subtitle {
  font-size: 1.25rem;
  color: var(--accent-primary);
  font-weight: 600;
  margin-bottom: 1rem;
}

.hero .bio {
  max-width: 680px;
  margin: 0 auto 2rem;
  color: var(--text-secondary);
  font-size: 1.05rem;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  transition: all 0.2s ease;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--accent-gradient);
  color: #ffffff;
  box-shadow: 0 4px 15px rgba(56, 189, 248, 0.25);
}

.btn-primary:hover {
  opacity: 0.92;
  transform: translateY(-2px);
}

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

.btn-secondary:hover {
  background: var(--bg-surface-hover);
  border-color: var(--accent-primary);
  transform: translateY(-2px);
}

/* Quick Links View Mode */
.quicklinks-wrapper {
  max-width: 540px;
  margin: 2rem auto 4rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.quicklinks-card {
  display: flex;
  align-items: center;
  padding: 1.1rem 1.4rem;
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  color: var(--text-primary);
  text-decoration: none;
  font-weight: 600;
  font-size: 1.05rem;
  transition: all 0.25s ease;
  box-shadow: var(--card-shadow);
  position: relative;
  overflow: hidden;
}

.quicklinks-card::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  height: 100%;
  width: 4px;
  background: var(--accent-gradient);
  opacity: 0;
  transition: opacity 0.25s ease;
}

.quicklinks-card:hover {
  transform: translateY(-3px);
  border-color: var(--accent-primary);
  background: var(--bg-surface-hover);
}

.quicklinks-card:hover::before {
  opacity: 1;
}

.quicklinks-icon {
  font-size: 1.5rem;
  margin-right: 1rem;
  width: 32px;
  text-align: center;
}

.quicklinks-text {
  flex: 1;
}

.quicklinks-text small {
  display: block;
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-weight: 400;
  margin-top: 0.1rem;
}

.quicklinks-arrow {
  color: var(--text-secondary);
  transition: transform 0.2s ease, color 0.2s ease;
}

.quicklinks-card:hover .quicklinks-arrow {
  transform: translateX(4px);
  color: var(--accent-primary);
}

/* Main Portfolio Sections */
section {
  padding: 3.5rem 0;
  border-top: 1px solid var(--border-color);
}

.section-title {
  font-size: 1.75rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
}

.section-subtitle {
  color: var(--text-secondary);
  margin-bottom: 2rem;
  font-size: 1rem;
}

/* Category Filters */
.filter-bar {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.filter-btn {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.4rem 1rem;
  border-radius: 9999px;
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
}

.filter-btn:hover, .filter-btn.active {
  background: var(--accent-gradient);
  color: #fff;
  border-color: transparent;
}

/* Project Cards Grid */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 1.5rem;
}

.project-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  transition: all 0.25s ease;
  box-shadow: var(--card-shadow);
}

.project-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent-primary);
}

.project-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 0.75rem;
}

.project-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
}

.project-links {
  display: flex;
  gap: 0.6rem;
}

.icon-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 1.1rem;
  transition: color 0.2s ease;
}

.icon-link:hover {
  color: var(--accent-primary);
}

.project-desc {
  color: var(--text-secondary);
  font-size: 0.925rem;
  margin-bottom: 1.25rem;
  flex: 1;
}

.project-highlights {
  list-style: none;
  margin-bottom: 1.25rem;
}

.project-highlights li {
  font-size: 0.85rem;
  color: var(--text-secondary);
  position: relative;
  padding-left: 1.2rem;
  margin-bottom: 0.35rem;
}

.project-highlights li::before {
  content: "▹";
  position: absolute;
  left: 0;
  color: var(--accent-primary);
}

.tags-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.tag {
  background: var(--tag-bg);
  color: var(--tag-text);
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-weight: 600;
}

/* Skills Grid */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
}

.skill-category {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
}

.skill-category h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--accent-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.skill-items {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.skill-pill {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 0.3rem 0.7rem;
  border-radius: var(--radius-md);
  font-size: 0.85rem;
  font-weight: 500;
}

/* Experience & Education Timeline */
.timeline {
  position: relative;
  padding-left: 2rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--border-color);
}

.timeline-item {
  position: relative;
  margin-bottom: 2.5rem;
}

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

.timeline-content {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
}

.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 0.5rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.timeline-role {
  font-size: 1.1rem;
  font-weight: 700;
}

.timeline-company {
  color: var(--accent-primary);
  font-weight: 600;
  font-size: 0.95rem;
}

.timeline-date {
  font-size: 0.85rem;
  color: var(--text-secondary);
  background: var(--bg-primary);
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

.timeline-bullets {
  list-style-type: disc;
  padding-left: 1.2rem;
  margin-top: 0.75rem;
  color: var(--text-secondary);
  font-size: 0.925rem;
}

.timeline-bullets li {
  margin-bottom: 0.4rem;
}

/* Footer */
footer {
  padding: 3rem 0;
  border-top: 1px solid var(--border-color);
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  margin-bottom: 1rem;
}

.footer-link {
  color: var(--text-primary);
  text-decoration: none;
  transition: color 0.2s ease;
}

.footer-link:hover {
  color: var(--accent-primary);
}

/* Toast Notification */
.toast {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  background: var(--accent-gradient);
  color: #fff;
  padding: 0.75rem 1.25rem;
  border-radius: var(--radius-md);
  font-weight: 600;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
  transform: translateY(100px);
  opacity: 0;
  transition: all 0.3s ease;
  z-index: 1000;
}

.toast.show {
  transform: translateY(0);
  opacity: 1;
}

/* Responsive Utilities */
.hidden {
  display: none !important;
}

@media (max-width: 640px) {
  .hero h1 {
    font-size: 2rem;
  }
  .hero-actions {
    flex-direction: column;
  }
  .timeline-header {
    flex-direction: column;
  }
}