:root {
  color-scheme: light;
  --ink: #14213d;
  --muted: #59657a;
  --primary: #215cc7;
  --primary-dark: #17469c;
  --sky: #dff4ff;
  --paper: #f8fbff;
  --line: #dce6f2;
  --sun: #ffd166;
  --coral: #ef6f61;
  --white: #ffffff;
  --shadow: 0 24px 70px rgba(25, 70, 140, 0.14);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  color: var(--ink);
  background: var(--paper);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 16px;
  line-height: 1.65;
}

a { color: inherit; }

.container {
  width: min(1120px, calc(100% - 40px));
  margin: 0 auto;
}

.nav {
  position: sticky;
  top: 0;
  z-index: 10;
  border-bottom: 1px solid rgba(220, 230, 242, 0.82);
  background: rgba(248, 251, 255, 0.9);
  backdrop-filter: blur(18px);
}

.nav-inner {
  min-height: 72px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  font-weight: 800;
  text-decoration: none;
}

.brand-mark {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border-radius: 13px;
  color: var(--white);
  background: var(--primary);
  box-shadow: 0 8px 22px rgba(33, 92, 199, 0.24);
}

.nav-links { display: flex; gap: 24px; }
.nav-links a { color: var(--muted); text-decoration: none; font-weight: 650; }
.nav-links a:hover { color: var(--primary); }

.hero {
  overflow: hidden;
  padding: 82px 0 70px;
  background:
    radial-gradient(circle at 82% 15%, rgba(255, 209, 102, 0.42), transparent 21rem),
    radial-gradient(circle at 10% 75%, rgba(111, 207, 245, 0.32), transparent 24rem),
    var(--paper);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.08fr 0.92fr;
  gap: 64px;
  align-items: center;
}

.eyebrow {
  margin: 0 0 14px;
  color: var(--primary);
  font-size: 0.86rem;
  font-weight: 850;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1, h2, h3 { margin-top: 0; line-height: 1.14; letter-spacing: -0.035em; }
h1 { max-width: 720px; margin-bottom: 22px; font-size: clamp(2.8rem, 6vw, 5.4rem); }
h2 { margin-bottom: 18px; font-size: clamp(2rem, 4vw, 3.25rem); }
h3 { margin-bottom: 9px; font-size: 1.2rem; }

.lead { max-width: 650px; margin: 0 0 30px; color: var(--muted); font-size: 1.18rem; }

.actions { display: flex; flex-wrap: wrap; gap: 12px; }

.button {
  display: inline-flex;
  min-height: 50px;
  align-items: center;
  justify-content: center;
  padding: 0 20px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--white);
  color: var(--ink);
  font-weight: 750;
  text-decoration: none;
}

.button.primary { border-color: var(--primary); background: var(--primary); color: var(--white); }
.button.primary:hover { background: var(--primary-dark); }

.trust-line { margin-top: 22px; color: var(--muted); font-size: 0.92rem; }

.phone {
  position: relative;
  width: min(360px, 100%);
  margin: 0 auto;
  padding: 18px;
  border: 10px solid #111a2d;
  border-radius: 48px;
  background: var(--white);
  box-shadow: var(--shadow);
}

.phone::before {
  content: "";
  position: absolute;
  top: 10px;
  left: 50%;
  width: 92px;
  height: 24px;
  transform: translateX(-50%);
  border-radius: 30px;
  background: #111a2d;
}

.phone-head { display: flex; justify-content: space-between; margin-top: 28px; font-weight: 800; }
.level-chip { padding: 4px 10px; border-radius: 999px; color: var(--primary); background: var(--sky); font-size: 0.82rem; }

.today-card {
  margin-top: 18px;
  padding: 24px;
  border-radius: 28px;
  text-align: center;
  background: linear-gradient(145deg, #e6f7ff, #eef2ff);
}

.today-card small { color: var(--primary); font-weight: 850; letter-spacing: 0.12em; }
.hanzi { margin: 8px 0 0; font-family: "Songti SC", "STSong", serif; font-size: 4.4rem; line-height: 1; }
.pinyin { margin: 4px 0 0; color: var(--primary); font-size: 1.15rem; }
.meaning { margin: 2px 0 0; font-weight: 750; }

.mini-list { display: grid; gap: 10px; margin-top: 16px; }
.mini-item { display: flex; align-items: center; gap: 12px; padding: 12px; border: 1px solid var(--line); border-radius: 16px; }
.mini-icon { display: grid; width: 38px; height: 38px; place-items: center; border-radius: 12px; background: var(--sky); }
.mini-item strong { display: block; font-size: 0.95rem; }
.mini-item span { color: var(--muted); font-size: 0.82rem; }

.section { padding: 92px 0; }
.section.white { background: var(--white); }
.section-head { max-width: 720px; margin-bottom: 42px; }
.section-head p { color: var(--muted); font-size: 1.05rem; }

.feature-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; }
.feature-card { padding: 24px; border: 1px solid var(--line); border-radius: 24px; background: var(--white); }
.feature-card .number { color: var(--primary); font-size: 0.84rem; font-weight: 850; letter-spacing: 0.1em; }
.feature-card p { margin-bottom: 0; color: var(--muted); }

.practice-grid { display: grid; grid-template-columns: 0.8fr 1.2fr; gap: 34px; align-items: start; }
.level-tabs { display: flex; gap: 10px; margin-bottom: 22px; }
.level-tab { padding: 10px 15px; border: 1px solid var(--line); border-radius: 999px; background: var(--white); cursor: pointer; font: inherit; font-weight: 750; }
.level-tab[aria-selected="true"] { border-color: var(--primary); color: var(--white); background: var(--primary); }
.word-stage { min-height: 320px; display: grid; place-items: center; padding: 34px; border-radius: 30px; background: var(--ink); color: var(--white); box-shadow: var(--shadow); }
.word-stage .hanzi { font-size: clamp(5rem, 12vw, 8rem); }
.word-stage .pinyin { color: #91dcff; }
.word-stage .meaning { font-size: 1.2rem; }

.steps { display: grid; gap: 18px; }
.step { display: grid; grid-template-columns: 44px 1fr; gap: 16px; padding: 19px; border-radius: 20px; background: rgba(255,255,255,0.75); }
.step-badge { display: grid; width: 44px; height: 44px; place-items: center; border-radius: 15px; background: var(--sun); font-weight: 900; }
.step p { margin: 4px 0 0; color: var(--muted); }

.privacy-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.privacy-card { padding: 26px; border-radius: 24px; background: var(--sky); }
.privacy-card:nth-child(2) { background: #fff3d4; }
.privacy-card:nth-child(3) { background: #f7e9ff; }
.privacy-card p { margin-bottom: 0; color: var(--muted); }

.faq { display: grid; gap: 12px; }
details { border: 1px solid var(--line); border-radius: 18px; background: var(--white); }
summary { padding: 18px 20px; cursor: pointer; font-weight: 750; }
details p { padding: 0 20px 20px; margin: 0; color: var(--muted); }

.page-hero { padding: 70px 0 42px; background: linear-gradient(180deg, var(--sky), var(--paper)); }
.page-hero p { max-width: 760px; color: var(--muted); font-size: 1.05rem; }
.document { max-width: 820px; padding: 54px 0 90px; }
.document h2 { margin: 42px 0 12px; font-size: 1.55rem; letter-spacing: -0.02em; }
.document h3 { margin-top: 28px; }
.document p, .document li { color: #334158; }
.document li + li { margin-top: 8px; }
.notice { padding: 18px 20px; border: 1px solid #efcf75; border-radius: 16px; background: #fff7dc; }
.meta { color: var(--muted); font-size: 0.92rem; }

.support-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin-top: 30px; }
.support-card { padding: 24px; border: 1px solid var(--line); border-radius: 22px; background: var(--white); }

.footer { padding: 34px 0; border-top: 1px solid var(--line); background: var(--white); }
.footer-inner { display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.footer-links { display: flex; flex-wrap: wrap; gap: 18px; }
.footer a { color: var(--muted); text-decoration: none; }
.footer a:hover { color: var(--primary); }

@media (max-width: 900px) {
  .hero-grid, .practice-grid { grid-template-columns: 1fr; }
  .hero-copy { text-align: center; }
  .lead { margin-inline: auto; }
  .actions { justify-content: center; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); }
  .privacy-grid { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .container { width: min(100% - 28px, 1120px); }
  .nav-inner { min-height: 64px; }
  .nav-links a:not(:last-child) { display: none; }
  .hero { padding-top: 54px; }
  .section { padding: 68px 0; }
  .feature-grid, .support-grid { grid-template-columns: 1fr; }
  .footer-inner { align-items: flex-start; flex-direction: column; }
  h1 { font-size: clamp(2.45rem, 13vw, 3.7rem); }
}