:root {
  --navy: #102A56;
  --navy-deep: #081A39;
  --blue: #4CA8FF;
  --blue-soft: #E8F4FF;
  --yellow: #FFD85C;
  --white: #FFFFFF;
  --ink: #12233F;
  --muted: #60708A;
  --line: rgba(16, 42, 86, 0.10);
  --shadow: 0 24px 64px rgba(26, 70, 124, 0.13);
  --shadow-soft: 0 12px 36px rgba(25, 75, 138, 0.09);
  --radius-lg: 32px;
  --radius-md: 24px;
  --radius-sm: 16px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 88px;
}

body {
  margin: 0;
  color: var(--ink);
  background: #F8FBFF;
  font-family: "Noto Sans SC", "Microsoft YaHei UI", "Microsoft YaHei", system-ui, sans-serif;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  padding-bottom: 90px;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -2;
  pointer-events: none;
  background-image: radial-gradient(rgba(76, 168, 255, 0.07) 1px, transparent 1px);
  background-size: 24px 24px;
  mask-image: linear-gradient(to bottom, #000, transparent 65%);
}

img,
video {
  max-width: 100%;
}

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

button,
a {
  -webkit-tap-highlight-color: transparent;
}

.container {
  width: min(1180px, calc(100% - 40px));
  margin-inline: auto;
}

.skip-link {
  position: fixed;
  z-index: 999;
  top: 8px;
  left: 8px;
  padding: 10px 16px;
  border-radius: 10px;
  color: var(--white);
  background: var(--navy);
  transform: translateY(-150%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: fixed;
  z-index: 100;
  inset: 0 0 auto;
  height: 76px;
  border-bottom: 1px solid transparent;
  transition: background 180ms ease, border-color 180ms ease, box-shadow 180ms ease;
}

.site-header.scrolled {
  background: rgba(248, 251, 255, 0.86);
  border-color: rgba(16, 42, 86, 0.08);
  box-shadow: 0 8px 32px rgba(16, 42, 86, 0.06);
  backdrop-filter: blur(18px);
}

.nav-shell {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--navy);
}

.brand img {
  display: block;
  border-radius: 13px;
  box-shadow: 0 8px 24px rgba(76, 168, 255, 0.22);
}

.brand span {
  display: grid;
  line-height: 1.1;
}

.brand b {
  font: 900 13px/1.2 "Arial Rounded MT Bold", Arial, sans-serif;
  letter-spacing: 0.12em;
}

.brand small {
  margin-top: 3px;
  color: #71819A;
  font-size: 11px;
  letter-spacing: 0.2em;
}

.desktop-nav {
  display: flex;
  align-items: center;
  gap: 36px;
  margin-left: auto;
  font-size: 14px;
  font-weight: 600;
  color: #4D607E;
}

.desktop-nav a {
  position: relative;
  padding-block: 8px;
}

.desktop-nav a::after {
  content: "";
  position: absolute;
  inset: auto 50% 0;
  height: 2px;
  background: var(--blue);
  transition: inset 160ms ease;
}

.desktop-nav a:hover::after,
.desktop-nav a:focus-visible::after {
  inset-inline: 0;
}

.nav-cta {
  padding: 10px 18px;
  border: 1px solid rgba(76, 168, 255, 0.26);
  border-radius: 999px;
  color: var(--navy);
  background: rgba(255, 255, 255, 0.68);
  box-shadow: 0 8px 24px rgba(40, 105, 175, 0.08);
  font-size: 13px;
  font-weight: 700;
}

.hero {
  position: relative;
  min-height: 720px;
  padding: 142px 0 50px;
  overflow: hidden;
  background:
    linear-gradient(115deg, rgba(232, 245, 255, 0.96), rgba(255, 255, 255, 0.76) 48%, rgba(232, 244, 255, 0.92)),
    radial-gradient(circle at 78% 42%, rgba(76, 168, 255, 0.22), transparent 38%);
}

.hero::before {
  content: "";
  position: absolute;
  top: -120px;
  right: -160px;
  width: 660px;
  height: 660px;
  border: 1px solid rgba(76, 168, 255, 0.14);
  border-radius: 50%;
  box-shadow: 0 0 0 80px rgba(76, 168, 255, 0.03), 0 0 0 160px rgba(76, 168, 255, 0.02);
}

.hero-orb {
  position: absolute;
  border-radius: 999px;
  filter: blur(4px);
}

.hero-orb-one {
  top: 115px;
  left: 4%;
  width: 80px;
  height: 80px;
  background: rgba(255, 216, 92, 0.18);
}

.hero-orb-two {
  right: 46%;
  bottom: 80px;
  width: 36px;
  height: 36px;
  background: rgba(76, 168, 255, 0.28);
}

.hero-grid {
  position: relative;
  z-index: 2;
  display: grid;
  grid-template-columns: minmax(0, 0.92fr) minmax(500px, 1.08fr);
  align-items: center;
  gap: 62px;
}

.hero-copy {
  padding-bottom: 12px;
}

.eyebrow,
.section-kicker {
  color: var(--blue);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.16em;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 7px 13px;
  border: 1px solid rgba(76, 168, 255, 0.22);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.62);
  box-shadow: inset 0 1px rgba(255, 255, 255, 0.82);
}

.eyebrow span {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--yellow);
  box-shadow: 0 0 0 5px rgba(255, 216, 92, 0.2);
}

.eyebrow em {
  font-style: normal;
}

.hero h1 {
  margin: 24px 0 20px;
  color: var(--navy);
  font-size: clamp(48px, 5.7vw, 78px);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.055em;
}

.hero h1 span {
  display: inline-block;
  position: relative;
  color: var(--blue);
  letter-spacing: -0.06em;
}

.hero h1 span::after {
  content: "";
  position: absolute;
  z-index: -1;
  left: -4px;
  right: -8px;
  bottom: 7px;
  height: 13px;
  border-radius: 999px;
  background: rgba(255, 216, 92, 0.56);
  transform: rotate(-1.5deg);
}

.hero-lead {
  max-width: 540px;
  margin: 0;
  color: #536681;
  font-size: clamp(17px, 2vw, 20px);
  line-height: 1.8;
}

.hero-actions {
  display: flex;
  align-items: center;
  gap: 28px;
  margin-top: 34px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 52px;
  padding: 0 24px;
  border: 0;
  border-radius: 14px;
  font-weight: 800;
  line-height: 1;
  transition: transform 160ms ease, box-shadow 160ms ease, filter 160ms ease;
}

.button:hover {
  transform: translateY(-2px);
}

.button:active {
  transform: translateY(0);
}

.button-primary {
  color: var(--white);
  background: linear-gradient(135deg, #217FDA, #4CA8FF);
  box-shadow: 0 16px 30px rgba(39, 132, 222, 0.27);
}

.play-dot {
  display: grid;
  width: 26px;
  height: 26px;
  place-items: center;
  border-radius: 50%;
  color: var(--blue);
  background: var(--white);
  font-size: 10px;
  padding-left: 2px;
}

.text-link {
  color: var(--navy);
  font-size: 14px;
  font-weight: 700;
}

.text-link span {
  display: inline-block;
  margin-left: 6px;
  transition: transform 160ms ease;
}

.text-link:hover span {
  transform: translateX(5px);
}

.hero-stats {
  display: flex;
  gap: 0;
  margin-top: 42px;
}

.stat-item {
  min-width: 116px;
  padding-right: 24px;
}

.stat-item + .stat-item {
  padding-left: 24px;
  border-left: 1px solid rgba(16, 42, 86, 0.12);
}

.stat-item b,
.stat-item small {
  display: block;
}

.stat-item b {
  color: var(--navy);
  font: 900 20px/1.25 "Arial Rounded MT Bold", "Microsoft YaHei", sans-serif;
}

.stat-item small {
  margin-top: 4px;
  color: #7C8A9F;
  font-size: 11px;
}

.hero-visual {
  position: relative;
  min-height: 480px;
}

.visual-halo {
  position: absolute;
  inset: 25px -40px 10px 65px;
  border-radius: 45% 55% 46% 54%;
  background: linear-gradient(145deg, rgba(76, 168, 255, 0.20), rgba(255, 216, 92, 0.12));
  filter: blur(2px);
  transform: rotate(-4deg);
}

.hero-image-frame {
  position: absolute;
  inset: 8px 0 8px 24px;
  overflow: hidden;
  border: 10px solid rgba(255, 255, 255, 0.78);
  border-radius: 46px 46px 110px 46px;
  background: var(--blue-soft);
  box-shadow: 0 36px 80px rgba(20, 74, 136, 0.22), inset 0 0 0 1px rgba(255, 255, 255, 0.9);
  transform: rotate(1.8deg);
}

.hero-image-frame img {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: cover;
  object-position: 63% center;
  transform: scale(1.02);
}

.image-sheen {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(120deg, rgba(255,255,255,0.22), transparent 30%, transparent 70%, rgba(76,168,255,0.1));
}

.floating-chip,
.learning-badge {
  position: absolute;
  z-index: 3;
  display: flex;
  align-items: center;
  border: 1px solid rgba(255, 255, 255, 0.7);
  background: rgba(255, 255, 255, 0.8);
  box-shadow: 0 16px 40px rgba(24, 69, 118, 0.18);
  backdrop-filter: blur(14px);
}

.floating-chip {
  gap: 9px;
  padding: 9px 15px 9px 9px;
  border-radius: 15px;
  color: var(--navy);
  font-size: 12px;
  font-weight: 800;
}

.floating-chip span {
  display: grid;
  width: 31px;
  height: 31px;
  place-items: center;
  border-radius: 10px;
  color: var(--white);
  background: var(--blue);
  font: 900 13px/1 "Nunito", sans-serif;
}

.chip-a {
  top: 58px;
  left: -12px;
  animation: float 5s ease-in-out infinite;
}

.chip-b {
  right: -20px;
  top: 132px;
  animation: float 5.7s ease-in-out -1.4s infinite;
}

.chip-b span {
  color: var(--navy);
  background: var(--yellow);
}

.learning-badge {
  left: -5px;
  bottom: 45px;
  gap: 11px;
  padding: 12px 16px;
  border-radius: 17px;
}

.badge-icon {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border-radius: 12px;
  color: var(--navy);
  background: var(--yellow);
  font-weight: 900;
}

.learning-badge div {
  display: grid;
}

.learning-badge small {
  color: #8290A4;
  font-size: 10px;
}

.learning-badge b {
  color: var(--navy);
  font-size: 13px;
}

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

.hero-bottom-note {
  position: relative;
  z-index: 2;
  display: flex;
  align-items: center;
  gap: 18px;
  margin-top: 42px;
  color: #8391A4;
  font-size: 11px;
  letter-spacing: 0.15em;
  text-align: center;
}

.hero-bottom-note p {
  flex: 0 0 auto;
  margin: 0;
}

.note-line {
  width: 100%;
  height: 1px;
  background: linear-gradient(to right, transparent, rgba(16, 42, 86, 0.12));
}

.note-line:last-child {
  background: linear-gradient(to left, transparent, rgba(16, 42, 86, 0.12));
}

.section {
  position: relative;
  padding: 112px 0;
}

.section-heading {
  display: grid;
  grid-template-columns: 1fr minmax(300px, 470px);
  align-items: end;
  gap: 50px;
  margin-bottom: 52px;
}

.section-kicker {
  margin: 0 0 12px;
  font-family: "Arial Rounded MT Bold", Arial, sans-serif;
}

.section-heading h2,
.system-copy h2,
.final-cta h2 {
  margin: 0;
  color: var(--navy);
  font-size: clamp(34px, 4.3vw, 52px);
  font-weight: 900;
  line-height: 1.2;
  letter-spacing: -0.045em;
}

.section-heading > p,
.system-copy > p {
  margin: 0;
  color: var(--muted);
  font-size: 16px;
  line-height: 1.9;
}

.path-section {
  background: var(--white);
}

.path-overview {
  position: relative;
  padding: 0 6px;
}

.path-track {
  position: absolute;
  z-index: 0;
  top: 44px;
  left: 5%;
  right: 5%;
  height: 4px;
  overflow: hidden;
  border-radius: 99px;
  background: #E9F0F8;
}

.path-track span {
  display: block;
  width: 0;
  height: 100%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--blue), #69D5C1, var(--yellow), #A98BFF);
  transition: width 1.3s cubic-bezier(.2,.8,.2,1);
}

.path-track.animated span {
  width: 100%;
}

.stage-list {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 13px;
}

.stage-card {
  position: relative;
  padding-top: 83px;
}

.stage-marker {
  position: absolute;
  top: 19px;
  left: 25px;
  display: grid;
  width: 52px;
  height: 52px;
  place-items: center;
  border: 8px solid var(--white);
  border-radius: 50%;
  color: var(--white);
  background: var(--accent);
  box-shadow: 0 7px 20px color-mix(in srgb, var(--accent) 30%, transparent);
  font: 900 12px/1 "Arial Rounded MT Bold", Arial, sans-serif;
}

.stage-content {
  height: 100%;
  min-height: 322px;
  padding: 28px 22px 24px;
  border: 1px solid rgba(16, 42, 86, 0.08);
  border-radius: 22px;
  background: var(--white);
  background: linear-gradient(155deg, color-mix(in srgb, var(--accent) 6%, white), white 52%);
  box-shadow: var(--shadow-soft);
  transition: transform 200ms ease, box-shadow 200ms ease, border-color 200ms ease;
}

.stage-card:hover .stage-content {
  transform: translateY(-7px);
  border-color: color-mix(in srgb, var(--accent) 30%, white);
  box-shadow: 0 20px 44px rgba(25, 75, 138, 0.14);
}

.stage-age {
  display: inline-flex;
  padding: 5px 10px;
  border-radius: 8px;
  color: var(--navy);
  background: color-mix(in srgb, var(--accent) 18%, white);
  font: 900 13px/1.3 "Arial Rounded MT Bold", "Microsoft YaHei", sans-serif;
}

.stage-content h3 {
  min-height: 52px;
  margin: 15px 0 11px;
  color: var(--navy);
  font-size: 18px;
  line-height: 1.45;
}

.stage-goal {
  min-height: 72px;
  margin: 0 0 16px;
  color: #697991;
  font-size: 13px;
  line-height: 1.8;
}

.stage-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.stage-tags span {
  padding: 5px 8px;
  border: 1px solid rgba(16, 42, 86, 0.07);
  border-radius: 7px;
  color: #61728A;
  background: rgba(249, 252, 255, 0.86);
  font-size: 11px;
}

.preview-section {
  overflow: hidden;
  background: linear-gradient(180deg, #F5FAFF, #EEF6FF);
}

.preview-section::before {
  content: "";
  position: absolute;
  top: 60px;
  right: -130px;
  width: 420px;
  height: 420px;
  border-radius: 50%;
  background: rgba(76, 168, 255, 0.08);
  filter: blur(1px);
}

.video-grid {
  position: relative;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

.video-card {
  overflow: hidden;
  border: 1px solid rgba(16, 42, 86, 0.08);
  border-radius: 28px;
  background: rgba(255, 255, 255, 0.86);
  box-shadow: var(--shadow);
  backdrop-filter: blur(12px);
}

.video-wrap {
  position: relative;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: #0B2148;
}

.video-wrap video {
  width: 100%;
  height: 100%;
  display: block;
  object-fit: cover;
}

.video-wrap::after {
  content: "试看课程";
  position: absolute;
  pointer-events: none;
  top: 16px;
  left: 16px;
  padding: 6px 11px;
  border: 1px solid rgba(255, 255, 255, 0.28);
  border-radius: 999px;
  color: var(--white);
  background: rgba(8, 26, 57, 0.52);
  backdrop-filter: blur(10px);
  font-size: 11px;
  font-weight: 700;
}

.video-placeholder {
  position: absolute;
  inset: 0;
  display: none;
  place-items: center;
  padding: 28px;
  text-align: center;
  color: rgba(255, 255, 255, 0.88);
  background:
    linear-gradient(rgba(8, 26, 57, 0.64), rgba(8, 26, 57, 0.72)),
    url("assets/cover.png") center/cover;
}

.video-placeholder.visible {
  display: grid;
}

.video-placeholder span {
  display: grid;
  width: 62px;
  height: 62px;
  margin: 0 auto 14px;
  place-items: center;
  border-radius: 50%;
  color: var(--navy);
  background: var(--yellow);
  box-shadow: 0 12px 28px rgba(0,0,0,.18);
  font-size: 18px;
}

.video-placeholder b,
.video-placeholder small {
  display: block;
}

.video-placeholder small {
  margin-top: 5px;
  color: rgba(255,255,255,.72);
}

.video-info {
  display: grid;
  grid-template-columns: 1fr;
  gap: 13px;
  padding: 22px 22px 24px;
}

.video-tag {
  display: inline-block;
  margin-bottom: 8px;
  color: var(--blue);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.12em;
}

.video-info h3 {
  margin: 0 0 8px;
  color: var(--navy);
  font-size: 18px;
  line-height: 1.45;
}

.video-info p {
  margin: 0;
  color: #6B7B91;
  font-size: 13px;
  line-height: 1.75;
}

.duration {
  align-self: start;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 10px;
  border-radius: 9px;
  color: var(--navy);
  background: var(--blue-soft);
  font-size: 11px;
  font-weight: 700;
  white-space: nowrap;
}

.video-note {
  margin: 26px 0 0;
  color: #74849A;
  font-size: 12px;
  text-align: center;
}

.video-note span {
  display: inline-grid;
  width: 18px;
  height: 18px;
  margin-right: 5px;
  place-items: center;
  border-radius: 50%;
  color: var(--navy);
  background: var(--yellow);
  font-size: 10px;
  font-weight: 900;
}

.system-section {
  overflow: hidden;
  background: var(--white);
}

.system-grid {
  display: grid;
  grid-template-columns: minmax(0, 760px);
  justify-content: center;
  align-items: center;
}

.system-copy h2 {
  margin-bottom: 22px;
}

.check-list {
  display: grid;
  gap: 12px;
  margin: 28px 0 0;
  padding: 0;
  list-style: none;
}

.check-list li {
  display: flex;
  align-items: center;
  gap: 11px;
  color: #435673;
  font-weight: 600;
}

.check-list span {
  display: grid;
  width: 24px;
  height: 24px;
  place-items: center;
  border-radius: 8px;
  color: var(--navy);
  background: var(--yellow);
  font-size: 12px;
  font-weight: 900;
}

.final-cta {
  overflow: hidden;
  padding: 100px 0 106px;
  color: var(--white);
  background:
    radial-gradient(circle at 82% 20%, rgba(76, 168, 255, 0.38), transparent 36%),
    linear-gradient(135deg, #0A224B, #123664 60%, #17477C);
}

.final-cta::before {
  content: "ABC";
  position: absolute;
  top: -35px;
  left: -20px;
  color: rgba(255,255,255,.025);
  font: 900 260px/1 "Arial Rounded MT Bold", Arial, sans-serif;
  letter-spacing: -0.08em;
}

.cta-orbit {
  position: absolute;
  top: -180px;
  right: -80px;
  width: 560px;
  height: 560px;
  border: 1px solid rgba(255,255,255,.09);
  border-radius: 50%;
  box-shadow: 0 0 0 55px rgba(255,255,255,.025), 0 0 0 110px rgba(255,255,255,.018);
}

.cta-content {
  position: relative;
  z-index: 1;
  text-align: center;
}

.section-kicker.light {
  color: #7EC0FF;
}

.final-cta h2 {
  color: var(--white);
}

.final-cta p:not(.section-kicker) {
  margin: 18px 0 32px;
  color: rgba(255,255,255,.68);
}

.button-yellow {
  color: var(--navy);
  background: var(--yellow);
  box-shadow: 0 16px 34px rgba(255, 216, 92, 0.2);
}

.button-yellow:hover {
  filter: brightness(1.04);
  box-shadow: 0 20px 40px rgba(255, 216, 92, 0.28);
}

.final-cta small {
  display: block;
  margin-top: 14px;
  color: rgba(255,255,255,.48);
  font-size: 11px;
}

.site-footer {
  padding: 38px 0;
  background: #07182F;
  color: rgba(255,255,255,.55);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.footer-brand {
  color: var(--white);
}

.footer-brand small {
  color: rgba(255,255,255,.46);
}

.footer-inner p,
.footer-inner a {
  margin: 0;
  font-size: 12px;
}

.footer-inner a:hover {
  color: var(--white);
}

.purchase-bar {
  position: fixed;
  z-index: 90;
  inset: auto 0 0;
  min-height: 76px;
  padding: 10px 0 calc(10px + env(safe-area-inset-bottom));
  border-top: 1px solid rgba(255,255,255,.55);
  background: rgba(255, 255, 255, 0.88);
  box-shadow: 0 -12px 44px rgba(16, 42, 86, 0.10);
  backdrop-filter: blur(20px);
}

.purchase-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.purchase-inner > div {
  display: grid;
}

.purchase-inner small {
  color: var(--blue);
  font-size: 10px;
  font-weight: 800;
  letter-spacing: .08em;
}

.purchase-inner strong {
  color: var(--navy);
  font-size: 16px;
}

.purchase-bar .button {
  min-height: 48px;
  border-radius: 13px;
}

.toast {
  position: fixed;
  z-index: 300;
  left: 50%;
  bottom: 104px;
  width: min(400px, calc(100% - 36px));
  padding: 13px 18px;
  border: 1px solid rgba(255,255,255,.16);
  border-radius: 13px;
  color: var(--white);
  background: rgba(8, 26, 57, 0.93);
  box-shadow: 0 18px 50px rgba(8,26,57,.22);
  font-size: 13px;
  text-align: center;
  opacity: 0;
  pointer-events: none;
  transform: translate(-50%, 12px);
  transition: opacity 180ms ease, transform 180ms ease;
}

.toast.visible {
  opacity: 1;
  transform: translate(-50%, 0);
}

.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 700ms ease, transform 700ms cubic-bezier(.2,.8,.2,1);
}

.reveal-delay {
  transition-delay: 100ms;
}

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

:focus-visible {
  outline: 3px solid rgba(76, 168, 255, 0.55);
  outline-offset: 4px;
}

@media (max-width: 1050px) {
  .hero {
    min-height: auto;
    padding-top: 130px;
  }

  .hero-grid {
    grid-template-columns: 1fr 0.95fr;
    gap: 34px;
  }

  .hero-visual {
    min-height: 430px;
  }

  .stage-list {
    grid-template-columns: repeat(6, minmax(0, 1fr));
    gap: 16px;
  }

  .stage-card {
    grid-column: span 2;
  }

  .stage-card:nth-child(4) {
    grid-column: 2 / span 2;
  }

  .path-track {
    display: none;
  }

  .stage-marker {
    top: 18px;
  }

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

@media (max-width: 820px) {
  body {
    padding-bottom: 80px;
  }

  .container {
    width: min(100% - 32px, 680px);
  }

  .site-header {
    height: 68px;
  }

  .desktop-nav,
  .nav-cta {
    display: none;
  }

  .hero {
    padding: 112px 0 46px;
  }

  .hero-grid {
    grid-template-columns: 1fr;
    gap: 42px;
  }

  .hero-copy {
    text-align: center;
  }

  .hero-lead {
    margin-inline: auto;
  }

  .hero-actions,
  .hero-stats {
    justify-content: center;
  }

  .hero-visual {
    min-height: 460px;
  }

  .hero-image-frame {
    inset-inline: 4%;
  }

  .hero-bottom-note {
    margin-top: 20px;
  }

  .section {
    padding: 84px 0;
  }

  .section-heading {
    grid-template-columns: 1fr;
    gap: 16px;
    margin-bottom: 38px;
    text-align: center;
  }

  .stage-list {
    display: grid;
    grid-template-columns: 1fr;
    gap: 18px;
  }

  .stage-card,
  .stage-card:nth-child(4) {
    grid-column: auto;
    padding: 0 0 0 64px;
  }

  .stage-card::before {
    content: "";
    position: absolute;
    top: 50px;
    bottom: -26px;
    left: 25px;
    width: 2px;
    background: linear-gradient(var(--accent), rgba(76, 168, 255, 0.1));
  }

  .stage-card:last-child::before {
    display: none;
  }

  .stage-marker {
    top: 18px;
    left: 0;
    border-width: 6px;
  }

  .stage-content {
    min-height: 0;
  }

  .stage-content h3,
  .stage-goal {
    min-height: 0;
  }

  .video-grid,
  .system-grid {
    grid-template-columns: 1fr;
  }

  .footer-inner {
    flex-wrap: wrap;
  }
}

@media (max-width: 560px) {
  .container {
    width: min(100% - 28px, 480px);
  }

  .brand img {
    width: 39px;
    height: 39px;
  }

  .hero {
    padding-top: 98px;
  }

  .hero h1 {
    margin-top: 20px;
    font-size: clamp(43px, 13.2vw, 62px);
  }

  .hero-lead {
    font-size: 16px;
    line-height: 1.8;
  }

  .hero-actions {
    display: grid;
    gap: 18px;
  }

  .hero-actions .button {
    width: 100%;
  }

  .hero-stats {
    margin-top: 34px;
  }

  .stat-item {
    min-width: 0;
    flex: 1;
    padding-right: 12px;
  }

  .stat-item + .stat-item {
    padding-left: 12px;
  }

  .stat-item b {
    font-size: 16px;
  }

  .stat-item small {
    font-size: 9px;
  }

  .hero-visual {
    min-height: 340px;
  }

  .hero-image-frame {
    inset: 0 2% 0 2%;
    border-width: 7px;
    border-radius: 30px 30px 72px 30px;
  }

  .chip-a {
    top: 24px;
    left: -2px;
  }

  .chip-b {
    top: 96px;
    right: -4px;
  }

  .learning-badge {
    left: -2px;
    bottom: 22px;
  }

  .hero-bottom-note {
    font-size: 9px;
    letter-spacing: .08em;
  }

  .section {
    padding: 72px 0;
  }

  .section-heading h2,
  .system-copy h2,
  .final-cta h2 {
    font-size: 34px;
  }

  .section-heading > p,
  .system-copy > p {
    font-size: 14px;
  }

  .stage-card {
    padding-left: 56px;
  }

  .stage-marker {
    width: 46px;
    height: 46px;
  }

  .stage-content {
    padding: 24px 20px;
  }

  .video-grid {
    gap: 20px;
  }

  .video-card {
    border-radius: 22px;
  }

  .video-info {
    grid-template-columns: 1fr;
    gap: 14px;
    padding: 21px;
  }

  .duration {
    grid-row: 1;
    justify-self: start;
  }

  .system-copy {
    text-align: center;
  }

  .check-list {
    display: inline-grid;
    text-align: left;
  }

  .final-cta {
    padding-block: 78px 86px;
  }

  .final-cta .button {
    width: 100%;
  }

  .footer-inner {
    justify-content: center;
    text-align: center;
  }

  .footer-inner p {
    width: 100%;
  }

  .purchase-bar {
    min-height: 70px;
  }

  .purchase-inner > div {
    display: none;
  }

  .purchase-bar .button {
    width: 100%;
  }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
  .reveal { opacity: 1; transform: none; }
}

@media print {
  .site-header,
  .purchase-bar,
  .toast { display: none; }
  body { padding-bottom: 0; }
  .hero { padding-top: 48px; }
  .reveal { opacity: 1; transform: none; }
}