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

/* === DARK DEFAULT === */
:root {
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --border-color: #334155;
  --primary-color: #3b82f6;
  --accent-color: #10b981;
  --border-radius: 8px;
  --transition: all 0.3s ease;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.3), 0 2px 4px -2px rgb(0 0 0 / 0.3);
}

/* === LIGHT MODE === */
[data-theme="light"] {
  --text-primary: #1e293b;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --border-color: #e2e8f0;
  --primary-color: #2563eb;
  --accent-color: #059669;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: var(--transition);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background-color: var(--bg-primary);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  transition: var(--transition);
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

.nav-brand h1 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary-color);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-secondary);
  font-weight: 500;
  transition: var(--transition);
  position: relative;
}

.nav-links a:hover {
  color: var(--primary-color);
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--primary-color);
  transition: width 0.3s ease;
}

.nav-links a:hover::after {
  width: 100%;
}

.theme-toggle {
  background: none;
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  padding: 0.5rem;
  cursor: pointer;
  color: var(--text-secondary);
  transition: var(--transition);
}

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

.mobile-menu-toggle {
  display: none;
  flex-direction: column;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
}

.mobile-menu-toggle span {
  width: 25px;
  height: 3px;
  background-color: var(--text-primary);
  margin: 3px 0;
  transition: var(--transition);
}

/* Hero Section */
.hero {
  padding: 8rem 0 4rem;
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
}

.hero-content {
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 800;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.5rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
  font-weight: 400;
}

.hero-description {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 3rem;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 2rem;
  border-radius: var(--border-radius);
  text-decoration: none;
  font-weight: 600;
  transition: var(--transition);
  border: none;
  cursor: pointer;
  font-size: 1rem;
}

.btn-primary {
  background-color: var(--primary-color);
  color: #fff;
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
  background-color: #1d4ed8;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.btn-outline {
  background-color: transparent;
  color: var(--primary-color);
  border: 2px solid var(--primary-color);
}

.btn-outline:hover {
  background-color: var(--primary-color);
  color: white;
}

.social-links {
  display: flex;
  gap: 1rem;
}

.social-links a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background-color: var(--bg-secondary);
  color: var(--text-secondary);
  text-decoration: none;
  transition: var(--transition);
  border: 1px solid var(--border-color);
}

.social-links a:hover {
  background-color: var(--primary-color);
  color: white;
  transform: translateY(-2px);
}

/* Sections */
section {
  padding: 4rem 0;
}

.section-title {
  font-size: 2.5rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 3rem;
  color: var(--text-primary);
}

/* About Section */
.about {
  background-color: var(--bg-secondary);
}

.about-content {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 4rem;
  align-items: start;
}

.about-text p {
  margin-bottom: 1.5rem;
  color: var(--text-secondary);
  font-size: 1.1rem;
  line-height: 1.7;
}

.tech-list {
  list-style: none;
  margin: 2rem 0;
}

.tech-list li {
  padding: 0.5rem 0;
  color: var(--text-secondary);
  position: relative;
  padding-left: 1.5rem;
}

.tech-list li::before {
  content: '▶';
  position: absolute;
  left: 0;
  color: var(--primary-color);
}

.basic-info {
  background-color: var(--bg-primary);
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
}

.basic-info h3 {
  margin-bottom: 1.5rem;
  color: var(--text-primary);
  font-size: 1.3rem;
}

.info-item {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.info-item i {
  color: var(--primary-color);
  width: 20px;
}

.info-item a {
  color: var(--text-secondary);
  text-decoration: none;
  transition: var(--transition);
}

.info-item a:hover {
  color: var(--primary-color);
}

/* Experience Section */
.timeline {
  position: relative;
  max-width: 800px;
  margin: 0 auto;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 30px;
  top: 0;
  bottom: 0;
  width: 2px;
  background-color: var(--border-color);
}

.timeline-item {
  position: relative;
  margin-bottom: 3rem;
  padding-left: 4rem;
}

.timeline-marker {
  position: absolute;
  left: 22px;
  top: 0;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background-color: var(--primary-color);
  border: 3px solid var(--bg-primary);
}

.timeline-content {
  background-color: var(--bg-primary);
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
}

.timeline-content h3 {
  font-size: 1.3rem;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.timeline-content h4 {
  margin-bottom: 0.5rem;
}

.timeline-content h4 a {
  color: var(--primary-color);
  text-decoration: none;
}

.timeline-content h4 a:hover {
  text-decoration: underline;
}

.timeline-date {
  display: inline-block;
  background-color: var(--bg-tertiary);
  color: var(--text-secondary);
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.9rem;
  margin-bottom: 1rem;
}

.timeline-content p {
  color: var(--text-secondary);
  line-height: 1.6;
}

.experience-note {
  text-align: center;
  margin-top: 3rem;
  color: var(--text-muted);
  font-style: italic;
}

/* Projects Section */
.projects {
  background-color: var(--bg-secondary);
}

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.project-card {
  background-color: var(--bg-primary);
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
  transition: var(--transition);
}

.project-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.project-card h3 {
  margin-bottom: 1rem;
  font-size: 1.3rem;
}

.project-card h3 a {
  color: var(--primary-color);
  text-decoration: none;
}

.project-card h3 a:hover {
  text-decoration: underline;
}

.project-card p {
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
  line-height: 1.6;
}

.tech-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tech-tag {
  background-color: var(--bg-tertiary);
  color: var(--text-secondary);
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.85rem;
  border: 1px solid var(--border-color);
}

.github-link {
  text-align: center;
}

/* Skills Section */
.skills-subtitle {
  text-align: center;
  color: var(--text-secondary);
  margin-bottom: 3rem;
  font-size: 1.1rem;
}

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

.skill-category {
  background-color: var(--bg-primary);
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
}

.skill-category h3 {
  margin-bottom: 1.5rem;
  color: var(--text-primary);
  font-size: 1.2rem;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.skill-tag {
  background-color: var(--bg-secondary);
  color: var(--text-secondary);
  padding: 0.5rem 1rem;
  border-radius: var(--border-radius);
  font-size: 0.9rem;
  border: 1px solid var(--border-color);
  transition: var(--transition);
  cursor: pointer;
}

.skill-tag:hover {
  background-color: var(--primary-color);
  color: white;
}

/* GitHub Section */
.github {
  background-color: var(--bg-secondary);
}

.github-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: start;
}

.github-profile {
  display: flex;
  gap: 1.5rem;
  align-items: center;
  background-color: var(--bg-primary);
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
}

.github-avatar {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  border: 3px solid var(--border-color);
}

.github-info h3 a {
  color: var(--primary-color);
  text-decoration: none;
  font-size: 1.3rem;
}

.github-info p {
  color: var(--text-muted);
  margin-bottom: 1rem;
}

.github-links {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.github-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9rem;
}

.github-links a:hover {
  color: var(--primary-color);
}

.github-activity {
  background-color: var(--bg-primary);
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
}

.github-activity h4 {
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.github-activity p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.github-activity small {
  color: var(--text-muted);
}

/* Education & Languages */
.education-languages {
  background-color: var(--bg-secondary);
}

.education-languages-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
}

.education h2,
.languages h2 {
  font-size: 2rem;
  margin-bottom: 2rem;
  color: var(--text-primary);
}

.education-item {
  background-color: var(--bg-primary);
  padding: 2rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
}

.education-item h3 {
  font-size: 1.3rem;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.education-item h4 {
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

.year {
  background-color: var(--bg-tertiary);
  color: var(--text-secondary);
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.9rem;
}

.language-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem;
  background-color: var(--bg-primary);
  border-radius: var(--border-radius);
  margin-bottom: 1rem;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-color);
}

.language {
  font-weight: 600;
  color: var(--text-primary);
}

.proficiency {
  color: var(--text-secondary);
}

/* Certificates */
.certificates {
  background-color: var(--bg-secondary);
}

.certificates-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1.5rem;
}

.certificate-item {
  background-color: var(--bg-primary);
  padding: 1.5rem;
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
  border: 1px solid var(--border-color);
  transition: var(--transition);
}

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

.certificate-item a {
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 500;
}

.certificate-item a:hover {
  text-decoration: underline;
}

/* Contact Section */
.contact {
  text-align: center;
}

.contact-content p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 3rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.contact-methods {
  display: flex;
  justify-content: center;
  gap: 2rem;
  flex-wrap: wrap;
}

.contact-method {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  padding: 2rem;
  background-color: var(--bg-secondary);
  border-radius: var(--border-radius);
  text-decoration: none;
  color: var(--text-secondary);
  transition: var(--transition);
  border: 1px solid var(--border-color);
  min-width: 150px;
}

.contact-method:hover {
  background-color: var(--primary-color);
  color: white;
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.contact-method i {
  font-size: 2rem;
}

/* Footer */
.footer {
  background-color: var(--bg-tertiary);
  padding: 2rem 0;
  text-align: center;
  border-top: 1px solid var(--border-color);
}

.footer p {
  color: var(--text-muted);
  font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  
  .mobile-menu-toggle {
    display: flex;
  }
  
  .hero-title {
    font-size: 2.5rem;
  }
  
  .hero-subtitle {
    font-size: 1.2rem;
  }
  
  .about-content {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
  
  .github-content {
    grid-template-columns: 1fr;
  }
  
  .education-languages-grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
  
  .contact-methods {
    flex-direction: column;
    align-items: center;
  }
  
  .projects-grid {
    grid-template-columns: 1fr;
  }
  
  .skills-grid {
    grid-template-columns: 1fr;
  }
  
  .certificates-grid {
    grid-template-columns: 1fr;
  }
  
  .timeline-item {
    padding-left: 2rem;
  }
  
  .timeline::before {
    left: 15px;
  }
  
  .timeline-marker {
    left: 7px;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 15px;
  }
  
  .nav {
    padding: 1rem 15px;
  }
  
  .hero {
    padding: 6rem 0 3rem;
  }
  
  .hero-title {
    font-size: 2rem;
  }
  
  .section-title {
    font-size: 2rem;
  }
  
  .github-profile {
    flex-direction: column;
    text-align: center;
  }
}

/* Mobile Navigation */
.nav-links.mobile-open {
  display: flex;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background-color: var(--bg-primary);
  flex-direction: column;
  padding: 1rem 2rem;
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-md);
}

/* Smooth scrolling */
html {
  scroll-behavior: smooth;
}

/* Focus styles for accessibility */
button:focus,
a:focus {
  outline: none;
}

/* Animation for theme transition */
* {
  transition: background-color 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}