:root {
  color-scheme: light;
  --bg: #f5f7f8;
  --surface: #ffffff;
  --surface-soft: #f9fbfc;
  --ink: #152127;
  --muted: #60717c;
  --subtle: #8a99a1;
  --border: #dce4e8;
  --primary: #126b5b;
  --primary-dark: #0d5146;
  --primary-soft: #e7f3f0;
  --blue: #2563eb;
  --blue-soft: #eaf1ff;
  --amber: #b7791f;
  --amber-soft: #fff5df;
  --shadow: 0 18px 46px rgba(18, 38, 49, 0.1);
  --radius: 8px;
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "PingFang SC", "Microsoft YaHei", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  background: var(--bg);
  color: var(--ink);
  letter-spacing: 0;
}

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

svg {
  width: 18px;
  height: 18px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 1.9;
}

.site-header,
.hero,
.section,
.cta-band,
.site-footer {
  width: min(1180px, calc(100% - 40px));
  margin: 0 auto;
}

.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 76px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-size: 19px;
  font-weight: 820;
}

.brand-mark {
  display: grid;
  width: 36px;
  height: 36px;
  place-items: center;
  border-radius: var(--radius);
  background: var(--primary);
  color: #fff;
  font-size: 17px;
  font-weight: 820;
}

.site-header nav,
.site-footer nav {
  display: flex;
  align-items: center;
  gap: 28px;
  color: var(--muted);
  font-size: 14px;
  font-weight: 700;
}

.site-header nav a:hover,
.site-footer nav a:hover,
.text-link:hover {
  color: var(--primary);
}

.nav-cta,
.primary-link,
.light-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  min-height: 42px;
  border-radius: var(--radius);
  font-size: 14px;
  font-weight: 780;
}

.nav-cta,
.primary-link {
  border: 1px solid var(--primary);
  background: var(--primary);
  color: #fff;
  box-shadow: 0 10px 24px rgba(18, 107, 91, 0.18);
}

.nav-cta {
  padding: 0 16px;
}

.primary-link {
  padding: 0 18px;
}

.nav-cta:hover,
.primary-link:hover {
  background: var(--primary-dark);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 0.92fr) minmax(460px, 1.08fr);
  gap: 54px;
  align-items: center;
  min-height: min(680px, calc(100vh - 124px));
  padding: 34px 0 40px;
}

.hero-copy h1 {
  max-width: 650px;
  margin: 0;
  color: var(--ink);
  font-size: 50px;
  line-height: 1.12;
  font-weight: 850;
}

.hero-copy p {
  max-width: 600px;
  margin: 24px 0 0;
  color: var(--muted);
  font-size: 17px;
  line-height: 1.8;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  align-items: center;
  margin-top: 34px;
}

.text-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--primary);
  font-size: 14px;
  font-weight: 780;
}

.proof-row {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin-top: 60px;
}

.proof-row div {
  border-left: 1px solid var(--border);
  padding-left: 18px;
}

.proof-row div:first-child {
  border-left: 0;
  padding-left: 0;
}

.proof-row strong,
.proof-row span {
  display: block;
}

.proof-row strong {
  margin-bottom: 6px;
  font-size: 15px;
}

.proof-row span {
  color: var(--muted);
  font-size: 13px;
}

.hero-visual {
  min-width: 0;
  align-self: center;
}

.teacher-hero-image {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  filter: drop-shadow(0 24px 48px rgba(18, 38, 49, 0.14));
}

.product-preview {
  display: grid;
  grid-template-columns: 150px minmax(0, 1fr);
  overflow: hidden;
  min-height: 560px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow);
}

.preview-rail {
  display: grid;
  align-content: start;
  gap: 9px;
  padding: 22px 16px;
  background: #083c37;
  color: rgba(255, 255, 255, 0.78);
}

.preview-logo {
  display: grid;
  width: 40px;
  height: 40px;
  margin-bottom: 12px;
  place-items: center;
  border-radius: var(--radius);
  background: #0f8a73;
  color: #fff;
  font-weight: 820;
}

.preview-rail span {
  min-height: 34px;
  padding: 9px 10px;
  border-radius: 6px;
  font-size: 13px;
  font-weight: 730;
}

.preview-rail .is-selected {
  background: rgba(255, 255, 255, 0.12);
  color: #fff;
}

.preview-main {
  min-width: 0;
  padding: 24px;
}

.preview-top {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  align-items: flex-start;
  margin-bottom: 18px;
}

.preview-top span {
  color: var(--muted);
  font-size: 12px;
  font-weight: 740;
}

.preview-top h2 {
  margin: 5px 0 0;
  font-size: 24px;
}

.live-chip {
  display: inline-flex;
  align-items: center;
  min-height: 30px;
  padding: 0 10px;
  border: 1px solid #bfe5d6;
  border-radius: 999px;
  background: var(--primary-soft);
  color: var(--primary) !important;
}

.preview-metrics {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.preview-metrics article,
.heat-card,
.chat-card,
.highlight-grid article {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
}

.preview-metrics article {
  padding: 15px;
}

.preview-metrics span {
  display: block;
  margin-bottom: 7px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 720;
}

.preview-metrics strong {
  font-size: 30px;
}

.preview-grid {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 14px;
  margin-top: 14px;
}

.heat-card,
.chat-card {
  min-height: 240px;
  padding: 18px;
  background: var(--surface-soft);
}

.heat-card h3,
.chat-card h3 {
  margin: 0 0 18px;
  font-size: 17px;
}

.heat-card div {
  display: grid;
  gap: 8px;
  margin-bottom: 18px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 720;
}

.heat-card b {
  display: block;
  height: 8px;
  border-radius: 999px;
  background: var(--primary);
}

.chat-card p {
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.65;
}

.chat-card .question {
  padding: 12px;
  border-radius: var(--radius);
  background: var(--primary);
  color: #fff;
}

.chat-card span {
  color: var(--subtle);
  font-size: 12px;
}

.section {
  padding: 74px 0;
  border-top: 1px solid var(--border);
}

.section-heading {
  max-width: 760px;
  margin: 0 auto 36px;
  text-align: center;
}

.section-heading h2,
.cta-band h2 {
  margin: 0;
  font-size: 36px;
  line-height: 1.2;
}

.section-heading p,
.cta-band p {
  margin: 14px 0 0;
  color: var(--muted);
  font-size: 16px;
  line-height: 1.75;
}

.highlight-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.highlight-grid article {
  min-height: 270px;
  padding: 26px;
  box-shadow: 0 10px 28px rgba(18, 38, 49, 0.05);
}

.icon-box {
  display: grid;
  width: 52px;
  height: 52px;
  place-items: center;
  border-radius: var(--radius);
  background: var(--primary-soft);
  color: var(--primary);
}

.icon-box.blue {
  background: var(--blue-soft);
  color: var(--blue);
}

.icon-box.amber {
  background: var(--amber-soft);
  color: var(--amber);
}

.highlight-grid h3,
.workflow h3 {
  margin: 22px 0 10px;
  font-size: 21px;
}

.highlight-grid p,
.workflow p,
.site-footer p {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.75;
}

.workflow-section {
  background: linear-gradient(180deg, transparent 0%, #fff 100%);
}

.workflow {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.workflow article {
  position: relative;
  min-height: 210px;
  padding: 24px 22px;
  border-top: 3px solid var(--primary);
  background: rgba(255, 255, 255, 0.66);
}

.workflow span {
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border-radius: 999px;
  background: var(--primary);
  color: #fff;
  font-size: 14px;
  font-weight: 820;
}

.cta-band {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 34px;
  margin-top: 18px;
  margin-bottom: 58px;
  padding: 44px;
  border-radius: var(--radius);
  background: var(--primary);
  color: #fff;
}

.cta-band p {
  max-width: 680px;
  color: rgba(255, 255, 255, 0.82);
}

.light-link {
  flex: 0 0 auto;
  border: 1px solid #fff;
  background: #fff;
  color: var(--primary-dark);
  padding: 0 18px;
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  padding: 34px 0 44px;
  border-top: 1px solid var(--border);
}

.site-footer p {
  max-width: 430px;
  margin-top: 12px;
}

@media (max-width: 1060px) {
  .hero {
    grid-template-columns: 1fr;
    min-height: 0;
  }

  .proof-row {
    margin-top: 42px;
  }

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

@media (max-width: 760px) {
  .site-header,
  .hero,
  .section,
  .cta-band,
  .site-footer {
    width: min(100% - 28px, 1180px);
  }

  .site-header {
    display: grid;
    min-height: 0;
    padding: 18px 0;
  }

  .site-header nav {
    order: 3;
    justify-content: space-between;
    gap: 12px;
  }

  .nav-cta {
    justify-self: start;
  }

  .hero {
    gap: 22px;
    padding: 24px 0 24px;
  }

  .hero-copy h1 {
    font-size: 38px;
  }

  .hero-copy p {
    font-size: 15px;
  }

  .proof-row,
  .highlight-grid,
  .workflow {
    grid-template-columns: 1fr;
  }

  .proof-row {
    display: none;
  }

  .product-preview {
    grid-template-columns: 1fr;
    min-height: 0;
  }

  .teacher-hero-image {
    width: 100%;
    max-width: 520px;
    margin: 0 auto;
  }

  .preview-rail {
    display: flex;
    overflow: auto;
    padding: 14px;
    scrollbar-width: none;
  }

  .preview-rail::-webkit-scrollbar {
    display: none;
  }

  .preview-logo {
    flex: 0 0 auto;
    margin-bottom: 0;
  }

  .preview-rail span {
    flex: 0 0 auto;
  }

  .preview-main {
    padding: 16px;
  }

  .preview-top {
    align-items: center;
    margin-bottom: 12px;
  }

  .preview-top h2 {
    font-size: 20px;
  }

  .preview-metrics {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 8px;
  }

  .preview-metrics article {
    padding: 10px;
  }

  .preview-metrics strong {
    font-size: 23px;
  }

  .preview-grid {
    display: none;
  }

  .section {
    padding: 54px 0;
  }

  .section-heading {
    text-align: left;
  }

  .section-heading h2,
  .cta-band h2 {
    font-size: 30px;
  }

  .cta-band,
  .site-footer {
    display: grid;
  }
}

@media (max-width: 460px) {
  .hero-copy h1 {
    font-size: 32px;
  }

  .primary-link,
  .text-link,
  .light-link,
  .nav-cta {
    width: 100%;
  }

  .preview-main,
  .highlight-grid article,
  .cta-band {
    padding: 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}