:root {
  --ink: #151411;
  --muted: #5f5a52;
  --paper: #fff9ed;
  --warm: #f5ead8;
  --blue: #1698f5;
  --green: #18b66a;
  --orange: #ff8a2d;
  --line: rgba(21, 20, 17, 0.12);
  --shadow: 0 24px 70px rgba(48, 33, 13, 0.16);
  --display: "Kaiti SC", "STKaiti", "Songti SC", "Noto Serif CJK SC", serif;
  --body: "Hiragino Sans GB", "PingFang SC", "Microsoft YaHei", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background:
    radial-gradient(circle at 82% 12%, rgba(22, 152, 245, 0.13), transparent 30rem),
    radial-gradient(circle at 4% 42%, rgba(255, 138, 45, 0.15), transparent 32rem),
    linear-gradient(135deg, #fffdf7 0%, #f7ecdb 48%, #eef8ff 100%);
  color: var(--ink);
  font-family: var(--body);
}

a {
  color: inherit;
}

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

.skip-link {
  position: absolute;
  left: 1rem;
  top: -4rem;
  z-index: 20;
  border-radius: 999px;
  background: var(--ink);
  color: white;
  padding: 0.75rem 1rem;
  transition: top 180ms ease;
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  padding: 1rem;
  backdrop-filter: blur(18px);
}

.nav-shell {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  max-width: 1180px;
  margin: 0 auto;
  border: 1px solid rgba(255, 255, 255, 0.65);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.72);
  box-shadow: 0 12px 34px rgba(48, 33, 13, 0.08);
  padding: 0.75rem 1rem;
}

.brand,
.nav-links {
  display: flex;
  align-items: center;
}

.brand {
  gap: 0.65rem;
  text-decoration: none;
  font-weight: 900;
  letter-spacing: -0.02em;
}

.brand-mark {
  width: 1.8rem;
  height: 1.8rem;
  border-radius: 50%;
  background:
    linear-gradient(90deg, transparent 47%, rgba(255, 255, 255, 0.75) 48% 52%, transparent 53%),
    linear-gradient(0deg, transparent 47%, rgba(255, 255, 255, 0.75) 48% 52%, transparent 53%),
    radial-gradient(circle at 50% 50%, var(--blue) 0 24%, transparent 25%),
    #d8efff;
  box-shadow: inset 0 0 0 1px rgba(22, 152, 245, 0.35);
}

.nav-links {
  gap: 0.25rem;
}

.nav-links a {
  border-radius: 999px;
  color: var(--muted);
  font-size: 0.94rem;
  font-weight: 750;
  padding: 0.6rem 0.9rem;
  text-decoration: none;
}

.nav-links a:hover,
.nav-links a:focus-visible,
.nav-links a[aria-current="page"] {
  background: rgba(22, 152, 245, 0.12);
  color: var(--ink);
  outline: none;
}

.hero-section {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(300px, 0.62fr);
  gap: clamp(2rem, 6vw, 5.5rem);
  align-items: center;
  max-width: 1180px;
  min-height: calc(100vh - 7rem);
  margin: 0 auto;
  padding: 3.8rem 1.25rem 6.5rem;
}

.eyebrow {
  color: var(--blue);
  font-size: 0.88rem;
  font-weight: 900;
  letter-spacing: 0.16em;
  margin: 0 0 1rem;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  margin: 0;
}

h1,
h2 {
  font-family: var(--display);
  font-weight: 900;
  letter-spacing: -0.06em;
}

h1 {
  font-size: clamp(3.1rem, 6.6vw, 6.7rem);
  line-height: 1.02;
}

h2 {
  font-size: clamp(2.6rem, 5.4vw, 5.6rem);
  line-height: 0.98;
}

h3 {
  font-size: 1.35rem;
  letter-spacing: -0.03em;
}

.hero-lede,
.section-lede,
.split-copy p,
.parents-copy p,
.final-cta p {
  color: var(--muted);
  font-size: clamp(1.05rem, 1.5vw, 1.35rem);
  font-weight: 650;
  line-height: 1.75;
}

.hero-lede {
  max-width: 42rem;
  margin: 1.6rem 0 0;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-top: 2.2rem;
}

.primary-action,
.secondary-action {
  border-radius: 999px;
  font-weight: 900;
  padding: 1rem 1.25rem;
  text-decoration: none;
}

.primary-action {
  background: var(--ink);
  color: white;
  box-shadow: 0 14px 34px rgba(21, 20, 17, 0.18);
}

.secondary-action {
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.58);
  color: var(--ink);
}

.primary-action:hover,
.secondary-action:hover,
.primary-action:focus-visible,
.secondary-action:focus-visible {
  outline: 3px solid rgba(22, 152, 245, 0.28);
  transform: translateY(-2px);
}

.hero-visual {
  position: relative;
  justify-self: center;
  max-width: 390px;
  width: min(100%, 390px);
}

.phone-frame {
  overflow: hidden;
  border: 0.8rem solid #090909;
  border-radius: 3rem;
  background: #090909;
  box-shadow: var(--shadow);
  transform: rotate(2.5deg);
}

.phone-frame img {
  width: 100%;
}

.promise-strip,
.story-section,
.split-section,
.training-section,
.parents-section,
.final-cta,
.policy-shell {
  max-width: 1180px;
  margin: 0 auto;
  padding-left: 1.25rem;
  padding-right: 1.25rem;
}

.promise-strip {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  padding-bottom: 7rem;
}

.promise-strip article,
.lesson-card,
.metric-board article,
.policy-card,
.policy-grid article {
  border: 1px solid rgba(255, 255, 255, 0.72);
  border-radius: 2rem;
  background: rgba(255, 255, 255, 0.62);
  box-shadow: 0 18px 52px rgba(48, 33, 13, 0.08);
}

.promise-strip article {
  padding: 1.35rem;
}

.promise-strip strong,
.promise-strip span {
  display: block;
}

.promise-strip strong {
  font-size: 1.25rem;
}

.promise-strip span {
  color: var(--muted);
  font-weight: 650;
  line-height: 1.6;
  margin-top: 0.55rem;
}

.story-section {
  padding-top: 2rem;
  padding-bottom: 7rem;
}

.section-kicker {
  display: inline-flex;
  border-radius: 999px;
  background: rgba(24, 182, 106, 0.13);
  color: var(--green);
  font-weight: 900;
  margin-bottom: 1.2rem;
  padding: 0.55rem 0.9rem;
}

.story-section .section-lede {
  max-width: 54rem;
}

.lesson-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-top: 2.2rem;
}

.lesson-card {
  min-height: 16rem;
  padding: 1.6rem;
}

.lesson-card span {
  display: inline-grid;
  place-items: center;
  width: 2.3rem;
  height: 2.3rem;
  border-radius: 50%;
  color: white;
  font-weight: 900;
  margin-bottom: 1.5rem;
}

.lesson-card.green span {
  background: var(--green);
}

.lesson-card.orange span {
  background: var(--orange);
}

.lesson-card.blue span {
  background: var(--blue);
}

.lesson-card p {
  color: var(--muted);
  font-weight: 650;
  line-height: 1.65;
}

.split-section {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(300px, 0.82fr);
  gap: clamp(2rem, 6vw, 5rem);
  align-items: center;
  padding-top: 2rem;
  padding-bottom: 7rem;
}

.device-card {
  overflow: hidden;
  border-radius: 2.2rem;
  box-shadow: var(--shadow);
}

.check-list {
  display: grid;
  gap: 0.8rem;
  margin: 1.5rem 0 0;
  padding: 0;
}

.check-list li {
  list-style: none;
  border-left: 0.35rem solid var(--blue);
  color: var(--muted);
  font-weight: 750;
  line-height: 1.55;
  padding-left: 0.9rem;
}

.training-section,
.parents-section,
.final-cta {
  border-radius: 3rem;
  margin-bottom: 7rem;
}

.training-section {
  background: rgba(255, 255, 255, 0.58);
  box-shadow: var(--shadow);
  padding-top: 3rem;
  padding-bottom: 3rem;
}

.training-path {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  margin: 2rem 0 1rem;
}

.training-path span {
  border-radius: 999px;
  background: rgba(22, 152, 245, 0.13);
  color: var(--blue);
  font-weight: 900;
  padding: 0.85rem 1rem;
}

.parents-section {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(300px, 0.7fr);
  gap: 2rem;
  align-items: center;
  padding-top: 3rem;
  padding-bottom: 3rem;
}

.metric-board {
  display: grid;
  gap: 1rem;
}

.metric-board article {
  padding: 1.35rem;
}

.metric-board strong,
.metric-board span {
  display: block;
}

.metric-board strong {
  color: var(--muted);
  font-size: 0.9rem;
}

.metric-board span {
  font-size: 2rem;
  font-weight: 950;
  margin-top: 0.35rem;
}

.final-cta {
  background: var(--ink);
  color: white;
  padding-top: 4rem;
  padding-bottom: 4rem;
}

.final-cta .eyebrow,
.final-cta a {
  color: #9fd8ff;
}

.final-cta p {
  color: rgba(255, 255, 255, 0.75);
}

.site-footer {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  justify-content: center;
  color: var(--muted);
  font-weight: 750;
  padding: 3rem 1.25rem;
}

.site-footer a {
  text-decoration: none;
}

.policy-shell {
  padding-top: 4rem;
  padding-bottom: 5rem;
}

.policy-hero {
  max-width: 860px;
  margin-bottom: 2rem;
}

.policy-hero h1 {
  font-size: clamp(3.2rem, 7vw, 6.5rem);
}

.policy-hero p {
  color: var(--muted);
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.7;
}

.policy-card,
.policy-grid article {
  margin-top: 1rem;
  padding: clamp(1.35rem, 3vw, 2.3rem);
}

.policy-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
}

.policy-card h2,
.policy-grid h2 {
  font-family: var(--body);
  font-size: 1.45rem;
  letter-spacing: -0.03em;
  margin-bottom: 0.85rem;
}

.policy-card p,
.policy-grid p,
.policy-grid li {
  color: var(--muted);
  font-size: 1rem;
  font-weight: 650;
  line-height: 1.8;
}

.policy-grid ul {
  display: grid;
  gap: 0.8rem;
  margin: 0;
  padding-left: 1.2rem;
}

.english-policy {
  background: rgba(239, 248, 255, 0.78);
}

.reveal {
  animation: rise-in 720ms cubic-bezier(0.2, 0.8, 0.2, 1) both;
}

.delay-1 {
  animation-delay: 120ms;
}

@keyframes rise-in {
  from {
    opacity: 0;
    transform: translateY(22px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 860px) {
  .nav-shell {
    border-radius: 1.35rem;
    align-items: flex-start;
    flex-direction: column;
  }

  .nav-links {
    flex-wrap: wrap;
  }

  .hero-section,
  .split-section,
  .parents-section,
  .policy-grid {
    grid-template-columns: 1fr;
  }

  .hero-section {
    padding-top: 3rem;
  }

  .promise-strip,
  .lesson-grid {
    grid-template-columns: 1fr;
  }

  .phone-frame {
    border-width: 0.55rem;
    border-radius: 2.4rem;
    transform: none;
  }

  .training-section,
  .parents-section,
  .final-cta {
    border-radius: 2rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .reveal {
    animation: none;
  }

  .primary-action:hover,
  .secondary-action:hover,
  .primary-action:focus-visible,
  .secondary-action:focus-visible {
    transform: none;
  }
}