:root {
  --bg: #0b1017;
  --panel: #121a25;
  --panel-soft: #192333;
  --text: #eef2f7;
  --muted: #9faec2;
  --line: #273449;
  --brand: #e4572e;
  --brand-strong: #ff6a3e;
  --ok: #26b67f;
  --radius: 16px;
  --shadow: 0 12px 30px rgba(0, 0, 0, 0.28);
  --container: min(1160px, calc(100vw - 3rem));
  --font-head: "Segoe UI", "Trebuchet MS", sans-serif;
  --font-body: "Segoe UI", Tahoma, sans-serif;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-body);
  color: var(--text);
  background:
    radial-gradient(1200px 700px at 8% -8%, rgba(228, 87, 46, 0.2), transparent 52%),
    radial-gradient(900px 520px at 100% 0%, rgba(56, 113, 255, 0.16), transparent 48%),
    linear-gradient(180deg, #0b1017, #091019 38%, #0a111c 100%);
  line-height: 1.6;
}

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

a:hover {
  color: #ffffff;
}

img,
svg,
canvas,
video {
  max-width: 100%;
  display: block;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 60;
  background: rgba(7, 11, 18, 0.84);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid rgba(39, 52, 73, 0.8);
}

.nav-shell {
  width: var(--container);
  margin: 0 auto;
  min-height: 70px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  position: relative;
}

.logo {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 1.3rem;
  letter-spacing: 0.04em;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  flex-wrap: nowrap;
}

.main-nav a {
  font-size: 0.95rem;
  color: #d5deea;
  padding: 0.42rem 0.72rem;
  border-radius: 999px;
  border: 1px solid transparent;
  transition: 140ms ease;
  white-space: nowrap;
}

.main-nav a:hover,
.main-nav a.active {
  color: #ffffff;
  border-color: rgba(228, 87, 46, 0.6);
  background: rgba(228, 87, 46, 0.16);
}

.nav-actions {
  display: flex;
  gap: 0.5rem;
}

.nav-action {
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--text);
  border-radius: 999px;
  padding: 0.42rem 0.8rem;
  cursor: pointer;
}

.mobile-nav-toggle {
  display: none;
}

.breadcrumb {
  width: var(--container);
  margin: 1rem auto 0;
  display: flex;
  align-items: center;
  gap: 0.55rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.hero {
  width: var(--container);
  margin: 1.2rem auto 0;
  min-height: 65vh;
  border-radius: 26px;
  overflow: hidden;
  border: 1px solid var(--line);
  background:
    linear-gradient(120deg, rgba(8, 13, 20, 0.92) 5%, rgba(8, 13, 20, 0.25) 56%, rgba(8, 13, 20, 0.9) 100%),
    var(--hero-image) center/cover no-repeat;
  box-shadow: var(--shadow);
}

.hero-content {
  width: 100%;
  min-height: inherit;
  display: grid;
  align-items: end;
  padding: clamp(1.2rem, 2.5vw, 2.1rem);
}

.hero-copy {
  max-width: 680px;
}

h1,
h2,
h3,
h4 {
  font-family: var(--font-head);
  line-height: 1.15;
  margin: 0;
  letter-spacing: 0.01em;
}

h1 {
  font-size: clamp(1.9rem, 4vw, 3.2rem);
}

h2 {
  font-size: clamp(1.45rem, 3vw, 2.2rem);
}

h3 {
  font-size: clamp(1.1rem, 2vw, 1.35rem);
}

p {
  margin: 0;
}

.eyebrow {
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: #f6beaa;
  margin-bottom: 0.35rem;
}

.meta {
  color: #a5b7cf;
  font-size: 0.85rem;
  letter-spacing: 0.03em;
}

.text-soft {
  color: var(--muted);
}

.scroll-cue {
  display: inline-block;
  margin-top: 0.9rem;
  color: #b2c2d7;
  font-size: 0.9rem;
}

.section {
  width: var(--container);
  margin: clamp(1.6rem, 3vw, 2.7rem) auto;
}

.section-intro {
  display: flex;
  justify-content: space-between;
  align-items: end;
  gap: 1.2rem;
  margin-bottom: 1rem;
}

.section-intro > p,
.section-intro > div + p {
  max-width: 580px;
}

.feature-band {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  min-height: 320px;
  overflow: hidden;
  box-shadow: var(--shadow);
  background:
    linear-gradient(130deg, rgba(7, 10, 15, 0.88), rgba(7, 10, 15, 0.25) 60%, rgba(7, 10, 15, 0.75)),
    var(--feature-image) center/cover no-repeat;
}

.feature-content {
  padding: 1.6rem;
  max-width: 760px;
}

.grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: 0.9rem;
}

.card {
  border: 1px solid var(--line);
  background: linear-gradient(180deg, rgba(24, 34, 48, 0.95), rgba(18, 26, 37, 0.95));
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 10px 24px rgba(0, 0, 0, 0.2);
}

.card-body {
  padding: 1rem;
  display: grid;
  gap: 0.5rem;
}

.card img {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

.span-12 {
  grid-column: span 12;
}

.span-8 {
  grid-column: span 8;
}

.span-6 {
  grid-column: span 6;
}

.span-4 {
  grid-column: span 4;
}

.span-3 {
  grid-column: span 3;
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  align-items: center;
}

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

input,
select,
textarea {
  background: #0f1723;
  border: 1px solid var(--line);
  color: var(--text);
  border-radius: 10px;
  padding: 0.56rem 0.7rem;
}

input::placeholder {
  color: #7f93ad;
}

button,
.button {
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--text);
  border-radius: 10px;
  padding: 0.52rem 0.85rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  cursor: pointer;
  transition: 120ms ease;
}

button:hover,
.button:hover {
  border-color: #a9b9cd;
  transform: translateY(-1px);
}

.button.primary,
button.primary {
  border-color: rgba(228, 87, 46, 0.92);
  background: linear-gradient(180deg, var(--brand-strong), var(--brand));
  color: white;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.55rem;
}

.quick-facts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 0.7rem;
}

.fact {
  border: 1px solid var(--line);
  background: rgba(18, 26, 37, 0.9);
  border-radius: 12px;
  padding: 0.8rem;
  display: grid;
  gap: 0.3rem;
}

.timeline {
  display: grid;
  gap: 0.65rem;
}

.timeline-item {
  border-left: 2px solid rgba(228, 87, 46, 0.65);
  padding-left: 0.8rem;
}

.lesson-pager {
  display: flex;
  justify-content: space-between;
  gap: 0.6rem;
  flex-wrap: wrap;
}

.quiz-item {
  border: 1px solid var(--line);
  border-radius: 14px;
  background: rgba(18, 26, 37, 0.9);
  padding: 1rem;
  display: grid;
  gap: 0.65rem;
}

.quiz-answer {
  display: none;
  color: #c7d5e7;
}

.quiz-item.show-answer .quiz-answer {
  display: block;
}

.telemetry-chart-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.telemetry-chart-card {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 0.5rem;
  background: rgba(10, 14, 21, 0.74);
}

.telemetry-chart-card canvas {
  width: 100%;
  height: 180px;
  border-radius: 10px;
  background: rgba(7, 11, 16, 0.9);
}

.telemetry-metrics {
  margin-top: 0.8rem;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.6rem;
}

.metric-chip {
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 0.7rem;
  background: rgba(15, 21, 31, 0.95);
}

.footer {
  width: var(--container);
  margin: 2rem auto 2.3rem;
}

.footer-grid {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1rem;
  background: rgba(13, 20, 29, 0.92);
}

.reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 320ms ease, transform 320ms ease;
}

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

@media (max-width: 1024px) {
  .span-3 {
    grid-column: span 6;
  }

  .span-4 {
    grid-column: span 6;
  }

  .telemetry-metrics {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 1120px) {
  .nav-shell {
    align-items: center;
    min-height: 62px;
    gap: 0.6rem;
  }

  .main-nav {
    display: none;
    position: absolute;
    top: calc(100% + 8px);
    right: 0;
    left: auto;
    width: min(320px, calc(100vw - 1rem));
    background: rgba(8, 12, 18, 0.98);
    border: 1px solid var(--line);
    border-radius: 12px;
    padding: 0.8rem;
    z-index: 70;
    box-shadow: var(--shadow);
    max-height: calc(100vh - 90px);
    overflow: auto;
  }

  .site-header.nav-open .main-nav {
    display: grid;
    gap: 0.55rem;
  }

  .main-nav a {
    display: block;
    width: 100%;
  }

  .mobile-nav-toggle {
    display: inline-flex;
    position: relative;
    width: 44px;
    height: 44px;
    min-width: 44px;
    padding: 0;
    border-radius: 10px;
    font-size: 0;
    color: transparent;
    overflow: hidden;
  }

  .mobile-nav-toggle::before,
  .mobile-nav-toggle::after {
    content: "";
    position: absolute;
    left: 10px;
    right: 10px;
    height: 2px;
    border-radius: 999px;
    background: #eef2f7;
    transition: transform 180ms ease, box-shadow 180ms ease, opacity 180ms ease;
  }

  .mobile-nav-toggle::before {
    top: 21px;
    box-shadow: 0 -7px 0 #eef2f7, 0 7px 0 #eef2f7;
  }

  .mobile-nav-toggle::after {
    top: 21px;
    opacity: 0;
  }

  .site-header.nav-open .mobile-nav-toggle::before {
    transform: rotate(45deg);
    box-shadow: none;
  }

  .site-header.nav-open .mobile-nav-toggle::after {
    transform: rotate(-45deg);
    opacity: 1;
  }

  .nav-actions {
    margin-left: auto;
  }

  .nav-actions .nav-action:not(.mobile-nav-toggle) {
    display: none;
  }

  .section-intro {
    flex-direction: column;
    align-items: flex-start;
  }

  .telemetry-chart-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 680px) {
  :root {
    --container: min(1160px, calc(100vw - 1.2rem));
  }

  .span-6,
  .span-8,
  .span-4,
  .span-3 {
    grid-column: span 12;
  }

  .hero {
    border-radius: 20px;
  }

  .button,
  button,
  input,
  select {
    width: 100%;
  }

  .controls {
    display: grid;
    grid-template-columns: 1fr;
  }

  .lesson-pager {
    display: grid;
  }

  .telemetry-metrics {
    grid-template-columns: 1fr;
  }
}