:root {
  --color-primary: #2563eb;
  --color-primary-dark: #1d4ed8;
  --color-primary-light: #dbeafe;
  --color-bg: #ffffff;
  --color-bg-alt: #f1f5f9;
  --color-bg-dark: #0f172a;
  --color-text: #1e293b;
  --color-text-light: #64748b;
  --color-text-lighter: #94a3b8;
  --color-border: #e2e8f0;
  --color-accent: #f59e0b;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
  --max-width: 1200px;
  --nav-height: 64px;
  --transition: 0.3s ease;
}

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

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans SC", sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

img {
  max-width: 100%;
  display: block;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 80px 0;
}

.section-alt {
  background: var(--color-bg-alt);
}

.section-title {
  font-size: clamp(24px, 3.5vw, 32px);
  font-weight: 700;
  text-align: center;
  margin-bottom: 48px;
  position: relative;
  color: var(--color-text);
}

.section-title::after {
  content: "";
  display: block;
  width: 60px;
  height: 4px;
  background: var(--color-primary);
  margin: 16px auto 0;
  border-radius: 2px;
}

/* ===== Navbar ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: background var(--transition);
}

.navbar.scrolled {
  background: rgba(255, 255, 255, 0.97);
  box-shadow: var(--shadow-sm);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 22px;
  font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.5px;
}

.nav-menu {
  display: flex;
  gap: 8px;
}

.nav-link {
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 500;
  color: var(--color-text-light);
  transition: all var(--transition);
}

.nav-link:hover,
.nav-link.active {
  color: var(--color-primary);
  background: var(--color-primary-light);
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  z-index: 1001;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition);
}

.nav-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.nav-toggle.active span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ===== Hero ===== */
.hero {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #0f172a 0%, #1e3a5f 50%, #2563eb 100%);
  color: #fff;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle at 30% 50%, rgba(37, 99, 235, 0.15) 0%, transparent 50%),
              radial-gradient(circle at 70% 30%, rgba(245, 158, 11, 0.1) 0%, transparent 50%);
  animation: heroBgFloat 20s ease-in-out infinite;
}

@keyframes heroBgFloat {
  0%, 100% { transform: translate(0, 0) rotate(0deg); }
  33% { transform: translate(30px, -30px) rotate(1deg); }
  66% { transform: translate(-20px, 20px) rotate(-1deg); }
}

.hero-content {
  position: relative;
  z-index: 1;
  animation: fadeInUp 0.8s ease;
}

.hero-avatar {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-accent), #ef4444);
  margin: 0 auto 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 28px;
  font-weight: 800;
  border: 3px solid rgba(255, 255, 255, 0.3);
  box-shadow: 0 0 40px rgba(37, 99, 235, 0.4);
}

.hero-avatar::after {
  content: attr(data-text);
}

.hero-name {
  font-size: clamp(36px, 6vw, 56px);
  font-weight: 800;
  letter-spacing: -1px;
  margin-bottom: 8px;
}

.hero-title {
  font-size: clamp(18px, 3vw, 24px);
  color: rgba(255, 255, 255, 0.8);
  font-weight: 400;
  margin-bottom: 32px;
}

.hero-info {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px 20px;
  margin-bottom: 24px;
}

.hero-info-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  color: rgba(255, 255, 255, 0.75);
  padding: 6px 12px;
  border-radius: 20px;
  background: rgba(255, 255, 255, 0.08);
  transition: all var(--transition);
}

.hero-info-item:hover {
  background: rgba(255, 255, 255, 0.15);
  color: #fff;
}

.hero-info-item svg {
  flex-shrink: 0;
}

.hero-flutter-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 14px;
  color: var(--color-accent);
  padding: 10px 20px;
  border: 1px solid rgba(245, 158, 11, 0.4);
  border-radius: 24px;
  transition: all var(--transition);
}

.hero-flutter-link:hover {
  background: rgba(245, 158, 11, 0.15);
  border-color: var(--color-accent);
}

.hero-scroll {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  animation: bounce 2s infinite;
}

.hero-scroll span {
  display: block;
  width: 24px;
  height: 40px;
  border: 2px solid rgba(255, 255, 255, 0.4);
  border-radius: 12px;
  position: relative;
}

.hero-scroll span::after {
  content: "";
  position: absolute;
  top: 8px;
  left: 50%;
  width: 4px;
  height: 8px;
  background: rgba(255, 255, 255, 0.6);
  border-radius: 2px;
  transform: translateX(-50%);
  animation: scrollDot 2s infinite;
}

@keyframes bounce {
  0%, 20%, 50%, 80%, 100% { transform: translateX(-50%) translateY(0); }
  40% { transform: translateX(-50%) translateY(-10px); }
  60% { transform: translateX(-50%) translateY(-5px); }
}

@keyframes scrollDot {
  0%, 100% { top: 8px; opacity: 1; }
  50% { top: 20px; opacity: 0.2; }
}

/* ===== Skills ===== */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 20px;
}

.skill-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 28px 20px;
  text-align: center;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.skill-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--color-primary);
  transform: scaleX(0);
  transition: transform var(--transition);
}

.skill-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
}

.skill-card:hover::before {
  transform: scaleX(1);
}

.skill-icon {
  margin-bottom: 12px;
}

.skill-card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--color-text);
}

.skill-card p {
  font-size: 13px;
  color: var(--color-text-light);
  margin-bottom: 16px;
  line-height: 1.5;
}

.skill-bar {
  height: 6px;
  background: var(--color-bg-alt);
  border-radius: 3px;
  overflow: hidden;
}

.skill-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent));
  border-radius: 3px;
  transition: width 1s ease 0.2s;
}

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

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

.timeline-item {
  position: relative;
  padding-left: 64px;
  padding-bottom: 40px;
}

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

.timeline-dot {
  position: absolute;
  left: 16px;
  top: 4px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--color-bg);
  border: 3px solid var(--color-primary);
  z-index: 1;
  transition: all var(--transition);
}

.timeline-item:hover .timeline-dot {
  background: var(--color-primary);
  box-shadow: 0 0 0 6px rgba(37, 99, 235, 0.15);
}

.timeline-content {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
  transition: all var(--transition);
}

.timeline-content:hover {
  box-shadow: var(--shadow);
  border-color: var(--color-primary-light);
}

.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 4px;
}

.timeline-header h3 {
  font-size: 17px;
  font-weight: 600;
}

.timeline-date {
  font-size: 13px;
  color: var(--color-primary);
  font-weight: 500;
  background: var(--color-primary-light);
  padding: 2px 10px;
  border-radius: 12px;
  white-space: nowrap;
}

.timeline-role {
  font-size: 14px;
  color: var(--color-text-light);
  margin-bottom: 12px;
}

.timeline-content ul {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.timeline-content li {
  font-size: 14px;
  color: var(--color-text-light);
  padding-left: 16px;
  position: relative;
}

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

/* ===== Filter ===== */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
  margin-bottom: 32px;
}

.filter-btn {
  padding: 8px 18px;
  border: 1px solid var(--color-border);
  border-radius: 24px;
  background: var(--color-bg);
  color: var(--color-text-light);
  font-size: 14px;
  cursor: pointer;
  transition: all var(--transition);
  font-family: inherit;
}

.filter-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.filter-btn.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
}

/* ===== Projects Grid ===== */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.project-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 20px;
  transition: all var(--transition);
  display: flex;
  flex-direction: column;
  gap: 8px;
  cursor: pointer;
}

.project-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
  border-color: var(--color-primary);
}

.project-card-arrow {
  font-size: 12px;
  color: var(--color-primary);
  opacity: 0;
  transform: translateX(-4px);
  transition: all var(--transition);
  margin-top: auto;
}

.project-card:hover .project-card-arrow {
  opacity: 1;
  transform: translateX(0);
}

.project-card.hidden {
  display: none;
}

.project-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.project-card-header h3 {
  font-size: 15px;
  font-weight: 600;
}

.project-badge {
  font-size: 11px;
  font-weight: 500;
  padding: 2px 8px;
  border-radius: 10px;
  background: var(--color-primary-light);
  color: var(--color-primary);
  white-space: nowrap;
}

.project-tech {
  font-size: 12px;
  color: var(--color-text-lighter);
  font-family: "SF Mono", "Fira Code", "Consolas", monospace;
}

.project-card p {
  font-size: 13px;
  color: var(--color-text-light);
  line-height: 1.5;
}

/* ===== Highlights ===== */
.highlights-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.highlight-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 28px 20px;
  text-align: center;
  transition: all var(--transition);
}

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

.highlight-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 56px;
  height: 56px;
  border-radius: 16px;
  background: var(--color-primary-light);
  color: var(--color-primary);
  margin-bottom: 16px;
}

.highlight-card h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
}

.highlight-card p {
  font-size: 14px;
  color: var(--color-text-light);
  line-height: 1.5;
}

/* ===== Footer ===== */
.footer {
  background: var(--color-bg-dark);
  color: rgba(255, 255, 255, 0.7);
  padding: 32px 0;
  text-align: center;
}

.footer .container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

.footer p {
  font-size: 14px;
}

.footer a {
  font-size: 14px;
  color: var(--color-accent);
  transition: color var(--transition);
}

.footer a:hover {
  color: #fff;
}

/* ===== Back to Top ===== */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: none;
  background: var(--color-primary);
  color: #fff;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all var(--transition);
  z-index: 999;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--color-primary-dark);
  transform: translateY(-3px);
}

/* ===== Scroll Reveal ===== */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

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

/* ===== Responsive: Tablet (768px - 1024px) ===== */
@media (max-width: 1024px) {
  .skills-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .projects-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .highlights-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* ===== Responsive: Mobile (< 768px) ===== */
@media (max-width: 768px) {
  .section {
    padding: 56px 0;
  }

  .section-title {
    margin-bottom: 32px;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-menu {
    position: absolute;
    top: calc(var(--nav-height) + 12px);
    right: 24px;
    left: auto;
    min-width: 180px;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
    padding: 12px;
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--color-border);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: all var(--transition);
    z-index: 1001;
  }

  .nav-menu.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
  }

  .nav-link {
    font-size: 15px;
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    text-align: left;
    display: block;
  }

  .hero-info {
    flex-direction: column;
    align-items: center;
    gap: 6px;
  }

  .skills-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }

  .skill-card {
    padding: 20px 14px;
  }

  .timeline::before {
    left: 18px;
  }

  .timeline-item {
    padding-left: 52px;
    padding-bottom: 32px;
  }

  .timeline-dot {
    left: 12px;
    width: 14px;
    height: 14px;
  }

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

  .filter-bar {
    gap: 6px;
  }

  .filter-btn {
    padding: 6px 14px;
    font-size: 13px;
  }

  .projects-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }

  .highlights-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
  }
}

/* ===== Responsive: Small Mobile (< 480px) ===== */
@media (max-width: 480px) {
  .skills-grid {
    grid-template-columns: 1fr 1fr;
    gap: 10px;
  }

  .skill-card {
    padding: 16px 12px;
  }

  .skill-card h3 {
    font-size: 14px;
  }

  .skill-card p {
    font-size: 12px;
  }

  .projects-grid {
    grid-template-columns: 1fr;
    gap: 10px;
  }
}

/* ===== Print ===== */
@media print {
  .navbar,
  .back-to-top,
  .hero-scroll,
  .nav-toggle {
    display: none !important;
  }

  .section {
    padding: 20px 0;
    break-inside: avoid;
  }

  .hero {
    min-height: auto;
    padding: 40px 0;
  }

  body {
    font-size: 12px;
  }
}