/* CSS Custom Properties for Theme Management */
:root {
  /* Light theme colors */
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --accent-primary: #3b82f6;
  --accent-secondary: #1d4ed8;
  --accent-gradient: linear-gradient(135deg, #3b82f6 0%, #1d4ed8 100%);
  --border-color: #e2e8f0;
  --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);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

  /* Typography */
  --font-family-base: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-family-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, 'Courier New', monospace;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  /* Border radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;

  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-normal: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;
}

/* Dark theme */
[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --accent-primary: #60a5fa;
  --accent-secondary: #3b82f6;
  --accent-gradient: linear-gradient(135deg, #60a5fa 0%, #3b82f6 100%);
  --border-color: #334155;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.3);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.4), 0 2px 4px -2px rgb(0 0 0 / 0.4);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.4), 0 4px 6px -4px rgb(0 0 0 / 0.4);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.4), 0 8px 10px -6px rgb(0 0 0 / 0.4);
}

/* Reset and base styles */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-family-base);
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color var(--transition-normal), color var(--transition-normal);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
}

h1 { font-size: clamp(2rem, 5vw, 3.5rem); }
h2 { font-size: clamp(1.75rem, 4vw, 2.5rem); }
h3 { font-size: clamp(1.5rem, 3vw, 2rem); }

p {
  color: var(--text-secondary);
  margin-bottom: var(--space-md);
}

a {
  color: var(--accent-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

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

/* Layout components */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

@media (max-width: 768px) {
  .container {
    padding: 0 var(--space-md);
  }
}

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

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--space-md) var(--space-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text-primary);
  text-decoration: none;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.theme-toggle {
  background: none;
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: var(--space-sm);
  cursor: pointer;
  font-size: 1.25rem;
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
}

.theme-toggle:hover {
  border-color: var(--accent-primary);
  transform: scale(1.05);
}

.theme-toggle:focus {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

/* Main content */
.main {
  padding-top: 80px;
}

/* Hero section */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: radial-gradient(circle at 30% 20%, rgba(59, 130, 246, 0.1) 0%, transparent 50%),
              radial-gradient(circle at 70% 80%, rgba(29, 78, 216, 0.1) 0%, transparent 50%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.hero-image {
  margin-bottom: var(--space-xl);
  animation: fadeInUp 0.8s ease-out;
}

.profile-picture {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--bg-primary);
  box-shadow: var(--shadow-xl);
  transition: all var(--transition-normal);
  background: var(--bg-secondary);
  /* Fallback for when image is loading */
  background-image: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
}

.profile-picture:hover {
  transform: scale(1.05);
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
}

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

.timeline::before {
    content: '';
    position: absolute;
    left: 50%;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--border-color);
    transform: translateX(-50%);
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
    display: flex;
    align-items: center;
}

.timeline-item:nth-child(odd) {
    flex-direction: row-reverse;
}

.timeline-marker {
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background: var(--primary-color);
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    z-index: 2;
    box-shadow: 0 0 0 4px var(--bg-primary);
}

.timeline-content {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: 0.5rem;
    box-shadow: var(--shadow-md);
    width: calc(50% - 2rem);
    position: relative;
}

.timeline-item:nth-child(odd) .timeline-content {
    margin-right: auto;
}

.timeline-item:nth-child(even) .timeline-content {
    margin-left: auto;
}

.timeline-content h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.timeline-content h4 {
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.timeline-date {
    color: var(--text-light);
    font-weight: 500;
    margin-bottom: 1rem;
}

.timeline-content ul {
    list-style: none;
    padding-left: 0;
}

.timeline-content li {
    position: relative;
    padding-left: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.timeline-content li::before {
    content: '▶';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-size: 0.8rem;
}

/* Placeholder styling when image fails to load */
.profile-picture::before {
  content: 'SC';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 3rem;
  font-weight: 800;
  color: white;
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.profile-picture:not([src]),
.profile-picture[src=""],
.profile-picture[src="profile-picture.jpg"] {
  position: relative;
}

.profile-picture:not([src])::before,
.profile-picture[src=""]::before,
.profile-picture[src="profile-picture.jpg"]::before {
  opacity: 1;
}

.hero-title {
  margin-bottom: var(--space-lg);
  animation: fadeInUp 0.8s ease-out;
}

.highlight {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: clamp(1.25rem, 3vw, 1.5rem);
  color: var(--text-secondary);
  margin-bottom: var(--space-md);
  animation: fadeInUp 0.8s ease-out 0.2s both;
}

.hero-description {
  font-size: clamp(1rem, 2.5vw, 1.125rem);
  color: var(--text-secondary);
  margin-bottom: var(--space-2xl);
  animation: fadeInUp 0.8s ease-out 0.4s both;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
  gap: var(--space-xl);
  margin-bottom: var(--space-2xl);
  animation: fadeInUp 0.8s ease-out 0.6s both;
}

.stat {
  text-align: center;
}

.stat-number {
  display: block;
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 800;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  margin-bottom: var(--space-xs);
}

.stat-label {
  font-size: 0.875rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.hero-actions {
  display: flex;
  gap: var(--space-lg);
  justify-content: center;
  flex-wrap: wrap;
  animation: fadeInUp 0.8s ease-out 0.8s both;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-xl);
  border-radius: var(--radius-lg);
  font-weight: 600;
  text-decoration: none;
  transition: all var(--transition-fast);
  cursor: pointer;
  border: none;
  font-size: 1rem;
  white-space: nowrap;
}

.btn-primary {
  background: var(--accent-gradient);
  color: white;
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  color: white;
}

.btn-secondary {
  background: var(--bg-secondary);
  color: var(--text-primary);
  border: 2px solid var(--border-color);
}

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

.btn:focus {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

/* Sections */
.about, .contact {
  padding: var(--space-3xl) 0;
}

.contact {
  background: var(--bg-tertiary);
}

.about {
  background: var(--bg-secondary);
}

.section-title {
  text-align: center;
  margin-bottom: var(--space-2xl);
  position: relative;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: -var(--space-md);
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 4px;
  background: var(--accent-gradient);
  border-radius: 2px;
}

.about-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-3xl);
  align-items: start;
}

@media (max-width: 768px) {
  .about-content {
    grid-template-columns: 1fr;
    gap: var(--space-2xl);
  }
}

.about-text p {
  font-size: 1.125rem;
  margin-bottom: var(--space-lg);
}

.skills h3 {
  margin-bottom: var(--space-lg);
  color: var(--text-primary);
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
}

.skill-tag {
  background: var(--bg-primary);
  color: var(--text-primary);
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  border: 1px solid var(--border-color);
  transition: all var(--transition-fast);
}

.skill-tag:hover {
  background: var(--accent-primary);
  color: white;
  transform: translateY(-2px);
}

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

.contact-description {
  font-size: 1.125rem;
  margin-bottom: var(--space-2xl);
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.social-links {
  display: flex;
  justify-content: center;
  gap: var(--space-xl);
  flex-wrap: wrap;
}

.social-link {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-lg) var(--space-xl);
  background: var(--bg-secondary);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-lg);
  color: var(--text-primary);
  font-weight: 600;
  transition: all var(--transition-fast);
  text-decoration: none;
  min-width: 140px;
  justify-content: center;
}

.social-link:hover {
  background: var(--accent-primary);
  border-color: var(--accent-primary);
  color: white;
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.social-link:focus {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

.social-link svg {
  flex-shrink: 0;
}

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

.footer p {
  color: var(--text-muted);
  margin: 0;
}

/* Animations */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Accessibility improvements */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  html {
    scroll-behavior: auto;
  }
}

/* Focus styles for keyboard navigation */
*:focus-visible {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
  :root {
    --border-color: #000000;
    --text-secondary: var(--text-primary);
  }

  [data-theme="dark"] {
    --border-color: #ffffff;
    --text-secondary: var(--text-primary);
  }
}

/* Mobile optimizations */
@media (max-width: 480px) {
  .profile-picture {
    width: 140px;
    height: 140px;
  }

  .hero-actions {
    flex-direction: column;
    align-items: center;
  }

  .btn {
    width: 100%;
    max-width: 280px;
    justify-content: center;
  }

  .social-links {
    flex-direction: column;
    align-items: center;
  }

  .social-link {
    width: 100%;
    max-width: 280px;
  }
}

/* Tablet optimizations */
@media (max-width: 768px) and (min-width: 481px) {
  .profile-picture {
    width: 160px;
    height: 160px;
  }
}

/* Print styles */
@media print {
  .header, .theme-toggle, .hero-actions {
    display: none;
  }

  .main {
    padding-top: 0;
  }

  body {
    background: white;
    color: black;
  }
}