:root {
  --ink: #172033;
  --muted: #5f6f84;
  --line: #d8e1eb;
  --paper: #fff;
  --wash: #f5f8fb;
  --blue: #2458cf;
  --green: #08785f;
  --gold: #b87514;
  --red: #c73546;
  --navy: #111d31;
  --cyan: #0e8ca5;
  --shadow: 0 18px 55px rgba(17, 29, 49, .12);
  font-family: Inter, "Segoe UI", "Microsoft YaHei", Arial, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; color: var(--ink); background: var(--wash); }
button, input, textarea, select { font: inherit; }
button { touch-action: manipulation; }

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 12px clamp(18px, 4vw, 56px);
  border-bottom: 1px solid rgba(216, 225, 235, .92);
  background: rgba(255, 255, 255, .94);
  backdrop-filter: blur(16px);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 220px;
  font-weight: 950;
}

.mark {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  background: var(--navy);
  color: #fff;
  display: grid;
  place-items: center;
}

.tabs { display: flex; justify-content: flex-end; gap: 8px; flex-wrap: wrap; }
.tab, .btn {
  border: 0;
  border-radius: 8px;
  padding: 10px 13px;
  cursor: pointer;
  font-weight: 850;
  color: var(--ink);
  background: #edf3fa;
  line-height: 1.2;
}
.tab.active, .btn.primary { background: var(--blue); color: #fff; }
.btn.green { background: var(--green); color: #fff; }
.btn.ghost { background: #fff; border: 1px solid var(--line); }
.btn:hover { transform: translateY(-1px); }

.screen { display: none; padding: clamp(28px, 5vw, 64px) clamp(18px, 5vw, 76px); }
.screen.active { display: block; }

.hero {
  min-height: calc(100vh - 62px);
  grid-template-columns: minmax(0, 1.05fr) minmax(360px, .86fr);
  gap: clamp(28px, 5vw, 54px);
  align-items: center;
  padding-top: 34px;
  background:
    linear-gradient(120deg, rgba(255,255,255,.96), rgba(239,247,250,.72)),
    var(--wash);
}
.hero.active { display: grid; }
.hero-copy { max-width: 860px; }

h1 {
  margin: 10px 0 18px;
  max-width: 950px;
  font-size: clamp(39px, 5.8vw, 74px);
  line-height: 1.03;
  letter-spacing: 0;
}
h2 {
  margin: 0 0 12px;
  font-size: clamp(30px, 4vw, 46px);
  line-height: 1.14;
  letter-spacing: 0;
}
h3 { margin: 0 0 10px; font-size: 21px; line-height: 1.25; }
p { line-height: 1.65; }
ul { padding-left: 20px; }

.lead {
  max-width: 780px;
  color: var(--muted);
  font-size: clamp(17px, 2vw, 22px);
  line-height: 1.7;
}
.eyebrow { color: var(--green); font-weight: 950; }
.muted { color: var(--muted); line-height: 1.65; }
.narrow { max-width: 440px; }

.hero-panel { position: relative; }
.hero-img {
  min-height: 520px;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: var(--shadow);
  background: url("assets/hero-ai-mastery.png") center/cover no-repeat;
  border: 1px solid rgba(255,255,255,.9);
}
.hero-card {
  position: absolute;
  left: 18px;
  right: 18px;
  bottom: 18px;
  display: grid;
  gap: 4px;
  padding: 16px;
  border-radius: 8px;
  color: #fff;
  background: rgba(17, 29, 49, .88);
  backdrop-filter: blur(10px);
}

.actions, .proof, .product-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 24px;
}
.actions.compact { margin-top: 0; }
.pill {
  border: 1px solid var(--line);
  background: rgba(255,255,255,.82);
  border-radius: 999px;
  padding: 8px 12px;
  color: var(--muted);
  font-weight: 800;
}

.strip {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  padding-top: 0;
  padding-bottom: 0;
  background: var(--line);
}
.stat {
  display: grid;
  gap: 5px;
  padding: 22px;
  background: #fff;
}
.stat strong { font-size: 25px; }
.stat span { color: var(--muted); }

.section-head {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 18px;
  margin-bottom: 18px;
}

.grid { display: grid; gap: 16px; }
.grid.four { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid.two, .layout { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.layout { display: grid; gap: 18px; align-items: start; }

.card {
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 20px;
  box-shadow: 0 8px 28px rgba(17,29,49,.06);
}
.product {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-height: 390px;
}
.offer-card {
  border-color: rgba(8, 120, 95, .32);
  box-shadow: 0 18px 50px rgba(8, 120, 95, .1);
}

.price {
  font-size: 34px;
  font-weight: 950;
  margin: 10px 0 6px;
}
.price small {
  font-size: 15px;
  color: var(--muted);
  margin-left: 4px;
}
.tag {
  display: inline-flex;
  width: fit-content;
  border-radius: 999px;
  padding: 6px 10px;
  background: #e9f7f3;
  color: var(--green);
  font-weight: 900;
  font-size: 13px;
}
.checklist li { margin: 8px 0; }

.paybox {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  align-items: start;
  margin-top: 18px;
}
.pay-card {
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}
.pay-card img {
  display: block;
  width: 100%;
  aspect-ratio: 1 / 1.28;
  object-fit: contain;
  background: #fff;
}
.pay-card figcaption {
  padding: 10px 12px;
  text-align: center;
  font-weight: 900;
}
.pay-card.wechat figcaption { color: var(--green); }
.pay-card.alipay figcaption { color: var(--blue); }
.payment-note {
  margin-top: 16px;
  padding: 14px;
  border: 1px solid #f1d39b;
  border-radius: 8px;
  background: #fff7e6;
}

.report-shell {
  display: grid;
  grid-template-columns: 1.05fr .95fr;
  gap: 16px;
  align-items: stretch;
}
.report-cover {
  background:
    linear-gradient(135deg, rgba(36, 88, 207, .08), rgba(8, 120, 95, .08)),
    #fff;
}
.report-score {
  display: grid;
  gap: 6px;
  padding: 14px;
  border: 1px solid rgba(36, 88, 207, .22);
  border-radius: 8px;
  background: #f7fbff;
}
.sample-mastery {
  display: grid;
  gap: 12px;
}
.sample-node {
  display: grid;
  gap: 8px;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
}
.sample-node strong {
  display: flex;
  justify-content: space-between;
  gap: 12px;
}
.timeline {
  display: grid;
  gap: 10px;
}
.timeline div {
  display: grid;
  grid-template-columns: 88px 1fr;
  gap: 12px;
  padding: 13px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfdff;
}
.timeline strong { color: var(--blue); }
.recommendation-card {
  border-color: rgba(8, 120, 95, .32);
}
.notice-line {
  margin-top: 14px;
  padding: 13px;
  border-radius: 8px;
  color: #6e4508;
  background: #fff7e6;
  border: 1px solid #f1d39b;
}

.choice {
  width: 100%;
  text-align: left;
  padding: 13px;
  margin: 10px 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fff;
  cursor: pointer;
}
.choice:hover { border-color: var(--blue); background: #edf4ff; }
.bar {
  height: 10px;
  border-radius: 999px;
  overflow: hidden;
  background: #e9eff6;
}
.bar i { display: block; height: 100%; width: 0; background: var(--green); }
.metric {
  display: grid;
  grid-template-columns: 120px 1fr 54px;
  align-items: center;
  gap: 10px;
  margin: 12px 0;
  font-weight: 850;
}
.node {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 14px;
  background: #fff;
  margin-bottom: 10px;
}
.node strong { display: flex; justify-content: space-between; gap: 10px; }
.weak { color: var(--red); }
.learn { color: var(--gold); }
.mastered { color: var(--green); }
.lesson {
  border-left: 4px solid var(--blue);
  padding: 14px;
  border-radius: 0 8px 8px 0;
  background: #f8fbff;
  margin: 10px 0;
}
.input {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: #fff;
}
.stack { display: grid; gap: 12px; }
.footer {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  padding: 30px clamp(18px, 5vw, 76px);
  background: var(--navy);
  color: #dce8ff;
}

@media (max-width: 1120px) {
  .grid.four { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 980px) {
  .topbar { align-items: flex-start; flex-direction: column; }
  .tabs { justify-content: flex-start; }
  .hero.active, .layout, .grid.four, .grid.three, .grid.two, .strip, .report-shell { grid-template-columns: 1fr; }
  .hero-img { min-height: 360px; }
  .section-head { display: grid; }
  .footer { display: grid; }
  .tabs .tab:not(.active) { display: none; }
}

@media (max-width: 560px) {
  .screen { padding-left: 16px; padding-right: 16px; }
  .brand { min-width: 0; }
  .actions .btn, .product-actions .btn { width: 100%; }
  .paybox { grid-template-columns: 1fr; }
  .pay-card img { aspect-ratio: 1 / 1.18; }
  .metric { grid-template-columns: 88px 1fr 48px; }
}