:root {
  --blue: #2f80ed;
  --blue-dark: #165bb8;
  --green: #27ae60;
  --orange: #f2994a;
  --yellow: #ffe08a;
  --ink: #123047;
  --muted: #5f7387;
  --soft: #f5fbff;
  --white: #ffffff;
  --line: #dbeaf3;
  --shadow: 0 20px 60px rgba(21, 73, 122, 0.14);
  --radius-lg: 28px;
  --radius-md: 18px;
  font-family: "Inter", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background: linear-gradient(180deg, #f7fcff 0%, #fffdf7 48%, #f7fff9 100%);
  line-height: 1.6;
}
a { color: inherit; text-decoration: none; }
button, input, select, textarea { font: inherit; }
button { cursor: pointer; }
.container { width: min(1120px, calc(100% - 40px)); margin: 0 auto; }
.section-pad { padding: 90px 0; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  backdrop-filter: blur(16px);
  background: rgba(255, 255, 255, 0.86);
  border-bottom: 1px solid rgba(219, 234, 243, 0.75);
}
.nav-shell {
  width: min(1180px, calc(100% - 32px));
  margin: 0 auto;
  min-height: 74px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}
.brand { display: inline-flex; align-items: center; gap: 10px; }
.brand-mark {
  width: 46px; height: 46px; display: grid; place-items: center;
  border-radius: 16px; color: white; font-weight: 900;
  background: linear-gradient(135deg, var(--blue), var(--green));
  box-shadow: 0 10px 25px rgba(47, 128, 237, 0.25);
}
.brand strong { display: block; font-size: 18px; line-height: 1.1; }
.brand small { display: block; color: var(--muted); font-size: 12px; }
.nav-links { display: flex; align-items: center; gap: 24px; font-weight: 700; color: #24485f; }
.nav-links a { transition: color .2s ease, transform .2s ease; }
.nav-links a:hover { color: var(--blue); transform: translateY(-1px); }
.nav-cta {
  padding: 10px 18px; color: white !important; border-radius: 999px;
  background: linear-gradient(135deg, var(--orange), #ffb84d);
  box-shadow: 0 10px 24px rgba(242, 153, 74, 0.28);
}
.nav-toggle { display: none; border: 0; background: transparent; padding: 8px; }
.nav-toggle span { display: block; width: 26px; height: 3px; border-radius: 4px; margin: 5px 0; background: var(--ink); }

.hero { position: relative; overflow: hidden; padding-top: 82px; }
.hero-grid { display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(330px, .75fr); gap: 56px; align-items: center; }
.hero-bg-orb { position: absolute; border-radius: 999px; filter: blur(1px); opacity: .55; z-index: -1; }
.orb-one { width: 280px; height: 280px; background: #d8f1ff; top: 105px; left: -100px; }
.orb-two { width: 240px; height: 240px; background: #fff0cf; right: -70px; top: 120px; }
.eyebrow {
  display: inline-flex; flex-wrap: wrap; align-items: center; gap: 10px;
  padding: 8px 14px; border: 1px solid var(--line); border-radius: 999px;
  background: rgba(255,255,255,.8); color: var(--muted); font-weight: 700;
}
.eyebrow span { color: var(--green); }
h1 { font-size: clamp(42px, 6vw, 72px); line-height: 1.05; margin: 24px 0; letter-spacing: -2px; }
h1 span { color: var(--blue); position: relative; }
h1 span::after { content: ""; position: absolute; height: 14px; left: 0; right: 0; bottom: 4px; background: rgba(255, 224, 138, .7); z-index: -1; border-radius: 99px; }
.hero-desc { max-width: 680px; font-size: 18px; color: var(--muted); margin-bottom: 30px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; margin-bottom: 34px; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  min-height: 48px; padding: 0 22px; border-radius: 999px; border: 0;
  font-weight: 900; transition: transform .2s ease, box-shadow .2s ease, background .2s ease;
}
.btn:hover { transform: translateY(-2px); }
.btn-primary { color: white; background: linear-gradient(135deg, var(--blue), #36a3ff); box-shadow: 0 16px 32px rgba(47,128,237,.28); }
.btn-soft { color: var(--blue-dark); background: #e9f5ff; }
.btn-card { width: 100%; background: white; color: var(--blue-dark); border: 1px solid rgba(47,128,237,.18); }
.trust-row { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 14px; max-width: 620px; }
.trust-row div { padding: 16px; background: rgba(255,255,255,.78); border: 1px solid var(--line); border-radius: 20px; }
.trust-row strong { display: block; font-size: 24px; color: var(--orange); }
.trust-row span { color: var(--muted); font-size: 14px; }

.hero-card { background: white; border-radius: 34px; box-shadow: var(--shadow); padding: 28px; border: 1px solid rgba(219,234,243,.9); transform: rotate(1deg); }
.card-topline, .progress-head, .course-meta { display: flex; justify-content: space-between; align-items: center; gap: 12px; }
.pill { padding: 6px 12px; border-radius: 999px; font-weight: 900; font-size: 13px; }
.live { background: #eafff2; color: var(--green); }
.stars { color: #ffbd2e; letter-spacing: 3px; }
.letter-stage { margin: 24px 0; padding: 24px; border-radius: 26px; background: linear-gradient(160deg, #edf7ff, #fff6e8); text-align: center; }
.big-letter { font-size: 124px; line-height: 1; font-weight: 1000; color: var(--blue); text-shadow: 8px 8px 0 #ffe08a; }
.sound-chip { display: inline-block; margin: 12px 0; padding: 6px 16px; border-radius: 999px; background: white; color: var(--orange); font-weight: 900; }
.mini-game { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.choice { border: 2px solid var(--line); background: #fff; border-radius: 18px; padding: 14px; font-weight: 1000; color: var(--ink); }
.choice.correct { background: #eafff2; border-color: var(--green); color: var(--green); }
.progress-widget { margin-top: 20px; }
.progress-bar { height: 12px; border-radius: 999px; background: #e8f1f7; overflow: hidden; }
.progress-bar span { display: block; height: 100%; border-radius: inherit; background: linear-gradient(90deg, var(--green), var(--blue)); }

.section-head { max-width: 760px; margin: 0 auto 42px; text-align: center; }
.section-head.left { margin-left: 0; text-align: left; }
.section-kicker { display: inline-block; color: var(--orange); font-weight: 1000; letter-spacing: .08em; margin-bottom: 10px; }
h2 { font-size: clamp(30px, 4vw, 46px); line-height: 1.15; margin: 0 0 14px; letter-spacing: -1px; }
.section-head p, .signup-copy p, .result-panel p { color: var(--muted); margin: 0; }
.course-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; align-items: stretch; }
.course-card { position: relative; padding: 28px; border-radius: var(--radius-lg); background: white; border: 1px solid var(--line); box-shadow: 0 14px 36px rgba(21,73,122,.08); }
.course-card.featured { transform: translateY(-12px); box-shadow: var(--shadow); }
.course-icon { width: 64px; height: 64px; border-radius: 20px; display: grid; place-items: center; color: white; font-size: 25px; font-weight: 1000; margin-bottom: 18px; }
.course-card.blue .course-icon { background: var(--blue); }
.course-card.green .course-icon { background: var(--green); }
.course-card.orange .course-icon { background: var(--orange); }
.course-meta span { color: var(--muted); font-weight: 800; font-size: 14px; }
.course-card h3, .teacher-card h3, .case-list h3 { margin: 12px 0 8px; font-size: 22px; }
.course-card p, .course-card li, .teacher-card p, .case-list p { color: var(--muted); }
.course-card ul { padding-left: 20px; margin: 18px 0 24px; }
.badge { position: absolute; top: 18px; right: 18px; background: #fff0d6; color: #b15d00; padding: 6px 12px; border-radius: 999px; font-weight: 1000; }

.path-section { background: rgba(237, 247, 255, .65); }
.path-layout { display: grid; grid-template-columns: .8fr 1.1fr; gap: 60px; align-items: start; }
.timeline { position: relative; display: grid; gap: 18px; }
.timeline::before { content: ""; position: absolute; left: 29px; top: 24px; bottom: 24px; width: 4px; border-radius: 999px; background: linear-gradient(var(--blue), var(--green), var(--orange)); }
.step { position: relative; display: grid; grid-template-columns: 62px 1fr; gap: 18px; padding: 20px; background: white; border: 1px solid var(--line); border-radius: 24px; box-shadow: 0 10px 26px rgba(21,73,122,.06); }
.step span { position: relative; z-index: 1; width: 62px; height: 62px; display: grid; place-items: center; border-radius: 50%; background: var(--ink); color: white; font-weight: 1000; }
.step h3 { margin: 0 0 4px; }
.step p { margin: 0; color: var(--muted); }

.teacher-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.teacher-card { padding: 28px; background: white; border: 1px solid var(--line); border-radius: var(--radius-lg); box-shadow: 0 14px 34px rgba(21,73,122,.07); }
.avatar { width: 76px; height: 76px; border-radius: 24px; display: grid; place-items: center; color: white; font-weight: 1000; font-size: 22px; margin-bottom: 14px; }
.avatar-blue { background: linear-gradient(135deg, var(--blue), #77c5ff); }
.avatar-green { background: linear-gradient(135deg, var(--green), #7be495); }
.avatar-orange { background: linear-gradient(135deg, var(--orange), #ffd36c); }
.role { font-weight: 900; color: var(--blue-dark) !important; }

.results-layout { display: grid; grid-template-columns: .95fr 1fr; gap: 28px; align-items: stretch; }
.result-panel { padding: 34px; border-radius: var(--radius-lg); background: linear-gradient(135deg, #ffffff, #eef8ff); border: 1px solid var(--line); }
.metrics { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-top: 26px; }
.metrics div { background: white; border-radius: 18px; padding: 16px; }
.metrics strong { display: block; color: var(--green); font-size: 24px; }
.metrics span { color: var(--muted); font-size: 13px; }
.case-list { display: grid; gap: 16px; }
.case-list article { background: white; border: 1px solid var(--line); border-radius: 24px; padding: 24px; box-shadow: 0 10px 28px rgba(21,73,122,.06); }
.case-list h3 { color: var(--blue-dark); }

.signup-section { background: linear-gradient(135deg, #eaf6ff, #fff7e8 60%, #ecfff3); }
.signup-layout { display: grid; grid-template-columns: .85fr 1fr; gap: 44px; align-items: start; }
.promise-card { margin-top: 24px; display: grid; gap: 12px; padding: 24px; background: white; border-radius: 24px; border: 1px solid var(--line); box-shadow: 0 12px 30px rgba(21,73,122,.08); }
.promise-card span::before { content: "✓"; color: var(--green); font-weight: 1000; margin-right: 8px; }
.signup-form { background: white; border-radius: 32px; padding: 30px; box-shadow: var(--shadow); border: 1px solid var(--line); }
.form-row { margin-bottom: 18px; }
.form-row label { display: block; font-weight: 900; margin-bottom: 8px; }
input, select, textarea { width: 100%; border: 1px solid #cfe1ec; border-radius: 16px; padding: 13px 14px; background: #fbfdff; color: var(--ink); outline: none; transition: border .2s, box-shadow .2s; }
input:focus, select:focus, textarea:focus { border-color: var(--blue); box-shadow: 0 0 0 4px rgba(47,128,237,.12); }
.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.error-text { display: block; min-height: 18px; color: #d92d20; font-weight: 800; font-size: 12px; margin-top: 4px; }
.invalid input, .invalid select { border-color: #d92d20; }
.submit-btn { width: 100%; min-height: 54px; font-size: 16px; }
.form-note { color: var(--muted); font-size: 13px; text-align: center; }
.success-message { display: none; margin-top: 16px; padding: 14px 16px; border-radius: 16px; background: #eafff2; color: #116b35; font-weight: 900; }
.success-message.show { display: block; }

.faq-layout { display: grid; grid-template-columns: .7fr 1fr; gap: 44px; }
.faq-list { display: grid; gap: 14px; }
details { background: white; border: 1px solid var(--line); border-radius: 20px; padding: 18px 20px; box-shadow: 0 8px 22px rgba(21,73,122,.05); }
summary { cursor: pointer; font-weight: 1000; font-size: 18px; }
details p { color: var(--muted); margin-bottom: 0; }
.site-footer { padding: 42px 0; background: #123047; color: white; }
.footer-grid { display: flex; justify-content: space-between; gap: 28px; align-items: center; }
.footer-brand small, .site-footer p { color: rgba(255,255,255,.72); }
.footer-links { display: flex; gap: 20px; font-weight: 800; }
.footer-links a:hover { color: #ffe08a; }

@media (max-width: 920px) {
  .nav-toggle { display: block; }
  .nav-links {
    position: absolute; left: 16px; right: 16px; top: 76px;
    display: none; flex-direction: column; align-items: stretch; gap: 8px;
    padding: 16px; background: white; border: 1px solid var(--line); border-radius: 22px; box-shadow: var(--shadow);
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px 14px; border-radius: 14px; }
  .nav-cta { text-align: center; }
  .hero-grid, .path-layout, .results-layout, .signup-layout, .faq-layout { grid-template-columns: 1fr; }
  .hero-grid { gap: 34px; }
  .course-grid, .teacher-grid { grid-template-columns: 1fr; }
  .course-card.featured { transform: none; }
  .section-pad { padding: 64px 0; }
}

@media (max-width: 620px) {
  .container { width: min(100% - 28px, 1120px); }
  .nav-shell { width: min(100% - 24px, 1180px); min-height: 68px; }
  .brand-mark { width: 42px; height: 42px; }
  h1 { letter-spacing: -1px; }
  .hero { padding-top: 50px; }
  .trust-row, .metrics, .two-col { grid-template-columns: 1fr; }
  .hero-card, .signup-form, .result-panel { padding: 22px; border-radius: 24px; }
  .big-letter { font-size: 96px; }
  .mini-game { gap: 8px; }
  .footer-grid { flex-direction: column; align-items: flex-start; }
  .footer-links { flex-wrap: wrap; }
}