:root {
  --bg: #eaf7ef;
  --surface: #ffffff;
  --surface-strong: #ecfbf0;
  --text: #0f172a;
  --muted: #4b5563;
  --border: #d1e7d3;
  --accent: #047857;
  --accent-strong: #0f766e;
  --accent-soft: rgba(6, 95, 70, 0.16);
  --shadow: 0 28px 80px rgba(15, 23, 42, 0.08);
  --bg-dark: #071811;
  --surface-dark: #0f172a;
  --text-dark: #e2e8f0;
  --muted-dark: #94a3b8;
  --border-dark: rgba(255, 255, 255, 0.14);
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  position: relative;
  font-family: "Inter", "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(180deg, #020617 0%, #071811 35%, #0f172a 100%);
  color: var(--text-dark);
  min-height: 100vh;
  transition: background 0.35s ease, color 0.35s ease;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background-image:
    radial-gradient(circle at 20% 20%, rgba(16, 185, 129, 0.18), transparent 24%),
    radial-gradient(circle at 82% 18%, rgba(5, 150, 105, 0.12), transparent 26%),
    linear-gradient(90deg, rgba(255, 255, 255, 0.12) 0%, rgba(255, 255, 255, 0.06) 50%, rgba(255, 255, 255, 0.12) 100%),
    repeating-linear-gradient(0deg, rgba(255,255,255,0.06), rgba(255,255,255,0.06) 1px, transparent 1px, transparent 6px),
    repeating-linear-gradient(90deg, rgba(255,255,255,0.06), rgba(255,255,255,0.06) 1px, transparent 1px, transparent 6px);
  opacity: 0.18;
  pointer-events: none;
  z-index: -1;
}

body.dark {
  background: linear-gradient(180deg, #020617 0%, #071811 35%, #0f172a 100%);
  color: var(--text-dark);
}

img,
picture,
svg,
iframe {
  max-width: 100%;
  display: block;
}

a {
  color: inherit;
}

button,
input,
select,
textarea,
a {
  font: inherit;
}

.skip-link {
  position: absolute;
  top: -3rem;
  left: 1rem;
  background: var(--accent);
  color: white;
  padding: 0.75rem 1rem;
  border-radius: 999px;
  z-index: 100;
  text-decoration: none;
  transition: top 0.2s ease;
}

.skip-link:focus-visible {
  top: 1rem;
}

header {
  text-align: center;
  background: linear-gradient(135deg, #047857, #10b981);
  color: white;
  padding: 2rem 1.5rem 2.5rem;
  position: relative;
  overflow: hidden;
}

header::after {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at top right, rgba(255, 255, 255, 0.24), transparent 22%);
  pointer-events: none;
}

header > * {
  position: relative;
  z-index: 1;
}

.logo {
  width: 110px;
  margin: 0 auto 1rem;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.2);
  padding: 0.75rem;
}

h1,
h2,
h3 {
  margin: 0;
}

h1 {
  font-size: clamp(2.5rem, 4vw, 4.25rem);
  line-height: 1.02;
}

header p {
  max-width: 720px;
  margin: 1rem auto 0;
  color: rgba(255, 255, 255, 0.92);
  line-height: 1.8;
}

.toggle-theme {
  position: absolute;
  top: 1.25rem;
  right: 1.25rem;
  border: 1px solid rgba(255, 255, 255, 0.24);
  background: rgba(255, 255, 255, 0.16);
  color: white;
  border-radius: 999px;
  padding: 0.85rem 1rem;
  cursor: pointer;
  transition: background 0.25s ease, transform 0.2s ease;
}

.toggle-theme:hover,
.toggle-theme:focus-visible {
  background: rgba(255, 255, 255, 0.28);
  transform: translateY(-1px);
}

nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75rem;
  margin-top: 1.75rem;
}

.nav-link {
  color: white;
  text-decoration: none;
  background: rgba(255, 255, 255, 0.18);
  padding: 0.7rem 1.1rem;
  border-radius: 999px;
  font-size: 0.95rem;
  transition: background 0.25s ease, transform 0.2s ease;
}

.nav-link:hover,
.nav-link:focus-visible {
  background: rgba(255, 255, 255, 0.3);
}

.nav-link.active {
  background: rgba(255, 255, 255, 0.32);
  font-weight: 700;
}

main {
  width: min(1200px, calc(100% - 2rem));
  margin: 0 auto;
  padding: 2.5rem 0 3rem;
}

section {
  margin: 0 auto 2.5rem;
  padding: 0;
}

.section-inner {
  background: rgba(255, 255, 255, 0.82);
  border: 1px solid rgba(255, 255, 255, 0.18);
  backdrop-filter: blur(18px);
  border-radius: 28px;
  box-shadow: var(--shadow);
  padding: 2rem;
}

.section-inner h2 {
  text-align: center;
  margin-bottom: 1.5rem;
}

body.dark .section-inner {
  background: rgba(15, 23, 42, 0.88);
  border-color: rgba(255, 255, 255, 0.10);
}

.hero {
  position: relative;
  padding: 2.5rem 1.5rem;
  text-align: center;
  background: rgba(255, 255, 255, 0.92);
  border-radius: 28px;
  border: 1px solid rgba(255, 255, 255, 0.25);
  box-shadow: var(--shadow);
  backdrop-filter: blur(14px);
}

body.dark .hero {
  background: rgba(15, 23, 42, 0.92);
  border-color: rgba(255, 255, 255, 0.12);
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 18% 20%, rgba(16, 185, 129, 0.12), transparent 24%),
              radial-gradient(circle at 82% 22%, rgba(5, 150, 105, 0.08), transparent 26%);
  pointer-events: none;
}

.hero .eyebrow {
  display: inline-flex;
  margin-bottom: 1rem;
  padding: 0.55rem 1rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.82rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.hero h2 {
  font-size: clamp(2rem, 3vw, 3rem);
  margin: 0.6rem auto 1rem;
  max-width: 12ch;
}

.hero p {
  max-width: 720px;
  margin: 0 auto;
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--muted);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem;
  margin-top: 2rem;
}

.code-bg {
  position: absolute;
  inset: 0;
  opacity: 0.38;
  pointer-events: none;
  background-image:
    radial-gradient(circle at 18% 18%, rgba(16, 185, 129, 0.14), transparent 24%),
    radial-gradient(circle at 82% 25%, rgba(5, 150, 105, 0.10), transparent 24%),
    linear-gradient(180deg, rgba(255,255,255,0.14), transparent 30%),
    repeating-linear-gradient(90deg, rgba(255,255,255,0.05) 0 1px, transparent 1px 6px);
}

.code-panel {
  position: absolute;
  width: min(340px, 38%);
  background: rgba(15, 23, 42, 0.38);
  border: 1px solid rgba(16, 185, 129, 0.22);
  border-radius: 22px;
  padding: 1rem;
  color: #dbeafe;
  font-family: "JetBrains Mono", "Fira Code", monospace;
  font-size: 0.95rem;
  line-height: 1.55;
  box-shadow: 0 22px 60px rgba(15, 23, 42, 0.22);
  backdrop-filter: blur(10px);
  animation: float 12s ease-in-out infinite;
}

body.dark .code-panel {
  background: rgba(15, 23, 42, 0.58);
  border-color: rgba(16, 185, 129, 0.30);
}

.code-panel.panel-1 {
  top: 2rem;
  left: 2rem;
  animation-delay: 0s;
}

.code-panel.panel-2 {
  top: 14rem;
  right: 3rem;
  animation-delay: 2s;
}

.code-panel.panel-3 {
  bottom: 2rem;
  left: 12rem;
  animation-delay: 4s;
}

.code-panel pre {
  margin: 0;
  white-space: pre-wrap;
}

.hero {
  position: relative;
  overflow: hidden;
}

.hero-content {
  position: relative;
  z-index: 1;
}

@keyframes float {
  0%, 100% {
    transform: translateY(0px);
  }
  50% {
    transform: translateY(-10px);
  }
}

.timeline-grid,
.resource-grid {
  display: grid;
  gap: 1.5rem;
  margin-top: 1.5rem;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.timeline-card,
.resource-card {
  background: rgba(255, 255, 255, 0.78);
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: 24px;
  box-shadow: var(--shadow);
  padding: 1.5rem;
}

body.dark .timeline-card,
body.dark .resource-card {
  background: rgba(15, 23, 42, 0.84);
  border-color: rgba(255, 255, 255, 0.10);
}

.timeline-card h3,
.resource-card h3,
.resource-card h4 {
  margin-bottom: 0.75rem;
}

.timeline-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 88px;
  height: 46px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 700;
  margin-bottom: 1rem;
  padding: 0 1rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.timeline-badge.badge-red {
  background: rgba(239, 68, 68, 0.14);
  color: #b91c1c;
}

.timeline-badge.badge-cyan {
  background: rgba(16, 185, 129, 0.18);
  color: #10b981;
}

.timeline-badge.badge-indigo {
  background: rgba(4, 120, 87, 0.16);
  color: #047857;
}

.timeline-badge.badge-blue {
  background: rgba(5, 150, 105, 0.16);
  color: #059669;
}

.timeline-badge.badge-gold {
  background: rgba(245, 158, 11, 0.14);
  color: #f59e0b;
}

.timeline-badge.badge-green {
  background: rgba(34, 197, 94, 0.14);
  color: #22c55e;
}

.resource-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.95rem 1.25rem;
  color: white;
  background: var(--accent);
  border-radius: 999px;
  text-decoration: none;
  transition: background 0.2s ease;
}

.resource-btn:hover,
.resource-btn:focus-visible {
  background: var(--accent-strong);
}

.resource-card p,
.timeline-card p,
.timeline-card ul,
.resource-card ul,
.section-inner p {
  color: var(--muted);
}

.section-inner ul,
.resource-card ul {
  margin-left: 1.25rem;
}

.hero-title {
  font-size: clamp(2.25rem, 4vw, 3.6rem);
  line-height: 1.02;
}

.register-btn.secondary {
  background: rgba(6, 95, 70, 0.12);
  color: var(--text);
  box-shadow: none;
}

.register-btn:hover,
.register-btn:focus-visible {
  transform: translateY(-1px);
}

.register-btn.secondary:hover,
.register-btn.secondary:focus-visible {
  background: rgba(6, 95, 70, 0.22);
}

footer {
  padding: 2.5rem 1rem;
  color: rgba(226, 232, 240, 0.82);
  font-size: 0.95rem;
  background: rgba(15, 23, 42, 0.72);
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}

.footer-inner {
  display: grid;
  grid-template-columns: minmax(220px, 1fr) auto;
  gap: 1.5rem;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
}

.footer-contact h3 {
  margin: 0 0 0.85rem;
  color: #ffffff;
  font-size: 1.05rem;
}

.footer-contact p {
  margin: 0.5rem 0;
  line-height: 1.7;
}

footer a {
  color: var(--accent);
  text-decoration: none;
}

.footer-brand {
  text-align: right;
}

.footer-brand img {
  width: 100px;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.08);
  padding: 0.75rem;
  display: inline-block;
}

.footer-brand p {
  margin: 0.9rem 0 0;
  color: rgba(226, 232, 240, 0.66);
}

.footer-copy {
  margin-top: 1.75rem;
  text-align: center;
  color: rgba(226, 232, 240, 0.68);
}

.video-grid,
.tutors-grid {
  display: grid;
  gap: 1.5rem;
}

.video-grid {
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  margin-top: 1.5rem;
}

.tutors-grid {
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  margin-top: 2rem;
}

.tutor-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 24px;
  box-shadow: var(--shadow);
  padding: 1.75rem;
  transition: transform 0.25s ease, border-color 0.25s ease;
}

body.dark .tutor-card {
  background: var(--surface-dark);
  border-color: var(--border-dark);
}

.tutor-card:hover {
  transform: translateY(-4px);
  border-color: rgba(4, 120, 87, 0.28);
}

.tutor-card h2 {
  font-size: 1.3rem;
  margin-bottom: 0.65rem;
}

.tutor-card p {
  margin: 0.55rem 0;
  color: var(--muted);
  line-height: 1.7;
}

.tutor-card img {
  width: 90px;
  height: 90px;
  object-fit: cover;
  border-radius: 999px;
  margin-bottom: 1rem;
}

.section-grid {
  display: grid;
  gap: 1.5rem;
}

button,
.register-btn,
.toggle-theme {
  font-weight: 600;
}

@media (max-width: 900px) {
  header {
    padding: 1.75rem 1rem 2rem;
  }
  .hero {
    padding: 1.75rem 1.25rem;
  }
}

@media (max-width: 720px) {
  nav {
    justify-content: center;
  }
  .hero h2 {
    max-width: 100%;
  }
  .hero-actions {
    flex-direction: column;
  }
  .register-btn {
    width: 100%;
  }
}

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