/* ===== CSS VARIABLES & THEMING ===== */
:root {
  /* Light mode (default) */
  --bg-primary: #f8f9fa;
  --bg-secondary: #ffffff;
  --bg-card: #ffffff;
  --text-primary: #1a1a2e;
  --text-secondary: #6c757d;
  --text-muted: #8892a0;
  --accent-primary: #6c63ff;
  --accent-secondary: #20c997;
  --accent-tertiary: #ff6b6b;
  --border-color: #e9ecef;
  --shadow-color: rgba(0, 0, 0, 0.08);
  --nav-bg: rgba(248, 249, 250, 0.95);

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

  /* Typography */
  --font-sans: 'JetBrains Mono', 'Courier New', monospace;
  --font-mono: 'JetBrains Mono', 'Courier New', monospace;

  /* Layout */
  --max-width: 800px;
  --nav-height: 60px;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-normal: 0.3s ease;
}

[data-theme="dark"] {
  --bg-primary: #0f0f1a;
  --bg-secondary: #1a1a2e;
  --bg-card: #1e1e32;
  --text-primary: #f5f5f5;
  --text-secondary: #a8b2c1;
  --text-muted: #6c7a8a;
  --border-color: #2a2a42;
  --shadow-color: rgba(0, 0, 0, 0.3);
  --nav-bg: rgba(15, 15, 26, 0.95);
}

/* ===== RESET & BASE ===== */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-height) + var(--spacing-lg));
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

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

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

/* ===== NAVIGATION ===== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: var(--nav-bg);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-md);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
}

.nav-logo-img {
  width: 32px;
  height: 32px;
  border-radius: 6px;
  object-fit: contain;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  font-family: var(--font-mono);
  font-size: 0.85rem;
}

.nav-links a {
  color: var(--text-secondary);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: 6px;
  transition: all var(--transition-fast);
}

.nav-links a:hover {
  color: var(--text-primary);
  background: var(--bg-secondary);
}

.nav-separator {
  color: var(--text-muted);
  user-select: none;
}

.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-xs);
  border-radius: 8px;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  justify-content: center;
}

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

.theme-toggle svg {
  width: 20px;
  height: 20px;
}

/* ===== MAIN CONTENT ===== */
main {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: calc(var(--nav-height) + var(--spacing-2xl)) var(--spacing-md) var(--spacing-2xl);
}

section {
  margin-bottom: var(--spacing-2xl);
}

/* ===== HERO / ABOUT SECTION ===== */
.hero {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: var(--spacing-lg);
  padding: var(--spacing-xl) 0;
}

.hero-image {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  object-fit: cover;
  border: 4px solid var(--border-color);
  box-shadow: 0 8px 32px var(--shadow-color);
}

.hero-greeting {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

.social-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--spacing-sm);
  font-family: var(--font-mono);
  font-size: 0.85rem;
}

.social-link {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: var(--spacing-xs) var(--spacing-sm);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.social-link:hover {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px var(--shadow-color);
}

.social-link svg {
  width: 16px;
  height: 16px;
}

.about-text {
  text-align: left;
  max-width: 100%;
  line-height: 1.8;
}

.about-text p {
  margin-bottom: var(--spacing-md);
  color: var(--text-secondary);
}

.about-text strong {
  color: var(--text-primary);
}

.highlight {
  color: var(--accent-primary);
  font-weight: 600;
}

/* ===== SECTION HEADERS ===== */
.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: var(--spacing-lg);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.section-title::before {
  content: '';
  width: 4px;
  height: 28px;
  background: linear-gradient(180deg, var(--accent-primary), var(--accent-secondary));
  border-radius: 2px;
}

/* ===== PROJECTS SECTION ===== */
.projects-grid {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

.project-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: var(--spacing-lg);
  display: grid;
  grid-template-columns: 80px 1fr;
  gap: var(--spacing-md);
  transition: all var(--transition-normal);
}

.project-card:hover {
  border-color: var(--accent-primary);
  box-shadow: 0 8px 32px var(--shadow-color);
  transform: translateY(-4px);
}

.project-thumbnail {
  width: 80px;
  height: 80px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
}

.project-content {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
}

.project-title {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text-primary);
  display: inline-block;
}

.project-title:hover {
  text-decoration: underline;
  color: var(--accent-primary);
}

.project-description {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.6;
}

.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
  margin-top: var(--spacing-xs);
}

.tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 4px 10px;
  border-radius: 6px;
  border: 1px solid;
  transition: all var(--transition-fast);
}

.tag-tech {
  border-color: var(--accent-secondary);
  color: var(--accent-secondary);
  background: transparent;
}

.tag-link {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  background: transparent;
  cursor: pointer;
}

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

.project-stats {
  display: flex;
  gap: var(--spacing-sm);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
}

.project-stats span {
  display: flex;
  align-items: center;
  gap: 4px;
}

/* ===== RESUME SECTION ===== */
.timeline {
  position: relative;
  padding-left: var(--spacing-lg);
}

.timeline::before {
  content: '';
  position: absolute;
  left: 6px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(180deg, var(--accent-primary), var(--accent-secondary), var(--text-muted));
  border-radius: 1px;
}

.timeline-item {
  position: relative;
  padding-bottom: var(--spacing-lg);
}

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

.timeline-item::before {
  content: '';
  position: absolute;
  left: calc(-1 * var(--spacing-lg) + 2px);
  top: 6px;
  width: 12px;
  height: 12px;
  background: var(--accent-primary);
  border: 3px solid var(--bg-primary);
  border-radius: 50%;
  z-index: 1;
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
  margin-bottom: var(--spacing-xs);
}

.timeline-title {
  font-weight: 600;
  color: var(--text-primary);
  font-size: 1rem;
}

.timeline-org {
  color: var(--accent-primary);
  font-weight: 500;
}

.timeline-date {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  white-space: nowrap;
}

.timeline-location {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: var(--spacing-xs);
}

.timeline-description {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.6;
}

/* ===== FOOTER ===== */
footer {
  text-align: center;
  padding: var(--spacing-xl) var(--spacing-md);
  color: var(--text-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--border-color);
}

.footer-credit {
  font-size: 0.7rem;
  margin-top: var(--spacing-xs);
  opacity: 0.7;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 640px) {
  .hero-greeting {
    font-size: 2rem;
  }

  .project-card {
    grid-template-columns: 1fr;
  }

  .project-thumbnail {
    width: 60px;
    height: 60px;
    font-size: 1.5rem;
  }

  .nav-links {
    display: none;
  }

  .timeline-header {
    flex-direction: column;
  }
}

/* ===== ANIMATIONS ===== */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.hero,
.project-card,
.timeline-item {
  animation: fadeInUp 0.6s ease forwards;
}

.project-card:nth-child(2) {
  animation-delay: 0.1s;
}

.project-card:nth-child(3) {
  animation-delay: 0.2s;
}

.timeline-item:nth-child(2) {
  animation-delay: 0.1s;
}

.timeline-item:nth-child(3) {
  animation-delay: 0.2s;
}

.timeline-item:nth-child(4) {
  animation-delay: 0.3s;
}