:root {
  --bg: #f5f6f2;
  --surface: #ffffff;
  --ink: #17221f;
  --muted: #5c6965;
  --brand: #0e6f62;
  --brand-dark: #0a5148;
  --accent: #d97706;
  --blue: #2563eb;
  --line: #dfe4de;
  --radius: 8px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", system-ui, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
}

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

button {
  font-family: inherit;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(10px);
}

.topbar-inner {
  max-width: 1120px;
  margin: 0 auto;
  padding: 12px 20px;
  display: flex;
  align-items: center;
  gap: 16px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 18px;
}

.brand-mark {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border-radius: var(--radius);
  background: var(--brand);
  color: #fff;
  font-size: 15px;
}

.nav {
  display: flex;
  gap: 18px;
  margin-left: auto;
  color: var(--muted);
  font-size: 14px;
}

.nav a:hover {
  color: var(--brand);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  padding: 0 18px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-size: 14px;
  cursor: pointer;
  transition: transform 0.12s ease, background 0.12s ease;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: var(--brand);
  color: #fff;
}

.btn-primary:hover {
  background: var(--brand-dark);
}

.btn-light {
  background: #fff;
  color: var(--ink);
}

.btn-ghost {
  border-color: rgba(255, 255, 255, 0.65);
  color: #fff;
}

.btn-sm {
  min-height: 34px;
  padding: 0 14px;
}

.hero {
  min-height: 74vh;
  display: flex;
  align-items: flex-end;
  padding: 88px 20px 96px;
  color: #fff;
  background:
    linear-gradient(180deg, rgba(9, 26, 22, 0.5), rgba(9, 26, 22, 0.78)),
    url("assets/hero-study.jpg") center 42% / cover no-repeat;
}

.hero-inner {
  width: 100%;
  max-width: 1120px;
  margin: 0 auto;
}

.hero-eyebrow {
  margin: 0 0 10px;
  font-size: 14px;
  letter-spacing: 0;
  color: #d8f0e8;
}

.hero h1 {
  margin: 0;
  font-size: 64px;
  line-height: 1.1;
}

.hero-sub {
  max-width: 560px;
  margin: 14px 0 26px;
  font-size: 17px;
  color: #e8f0ed;
}

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

.band {
  padding: 72px 20px;
}

.band-alt {
  background: var(--surface);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.wrap {
  max-width: 1120px;
  margin: 0 auto;
}

.wrap-narrow {
  max-width: 820px;
}

.section-head {
  margin-bottom: 34px;
}

.kicker {
  margin: 0 0 8px;
  color: var(--brand);
  font-size: 13px;
  font-weight: 700;
}

.section-head h2 {
  margin: 0;
  font-size: 30px;
  line-height: 1.25;
}

.section-sub {
  margin: 10px 0 0;
  color: var(--muted);
}

.subject-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
}

.subject-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px;
  display: flex;
  gap: 14px;
  align-items: flex-start;
}

.subject-mark {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: var(--radius);
  color: #fff;
  font-weight: 700;
}

.subject-mark-yw { background: #b45309; }
.subject-mark-sx { background: #2563eb; }
.subject-mark-yy { background: #0e7490; }
.subject-mark-wl { background: #7c3aed; }
.subject-mark-hx { background: #c2410c; }
.subject-mark-sw { background: #15803d; }
.subject-mark-ls { background: #a16207; }
.subject-mark-dl { background: #0369a1; }
.subject-mark-df { background: #be123c; }

.subject-card h3 {
  margin: 0 0 4px;
  font-size: 16px;
}

.subject-card p {
  margin: 0;
  color: var(--muted);
  font-size: 13px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
}

.feature-card {
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  min-height: 168px;
  display: flex;
  flex-direction: column;
}

.feature-card h3 {
  margin: 0 0 8px;
  font-size: 16px;
}

.feature-card p {
  margin: 0 0 14px;
  color: var(--muted);
  font-size: 13px;
  flex: 1;
}

.feature-tag {
  align-self: flex-start;
  padding: 3px 9px;
  border-radius: 999px;
  background: #e6efe9;
  color: var(--brand-dark);
  font-size: 12px;
}

.preview-wrap {
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: 56px;
  align-items: center;
}

.phone {
  width: 300px;
  margin: 0 auto;
  padding: 10px;
  border-radius: 30px;
  background: #111c19;
  box-shadow: 0 18px 40px rgba(20, 40, 34, 0.18);
}

.phone-screen {
  border-radius: 22px;
  background: #f7faf7;
  padding: 14px;
  min-height: 520px;
  overflow: hidden;
}

.ps-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2px 12px;
  font-weight: 700;
  font-size: 15px;
}

.ps-bar i {
  width: 54px;
  height: 16px;
  border-radius: 10px;
  background: #d7ddd7;
}

.ps-search {
  padding: 9px 12px;
  border-radius: 10px;
  background: #e9eeea;
  color: #7b8581;
  font-size: 12px;
}

.ps-subjects {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin: 12px 0;
}

.ps-subjects span {
  padding: 5px 10px;
  border-radius: 999px;
  background: #ffffff;
  border: 1px solid #dbe1dc;
  color: #54605c;
  font-size: 12px;
}

.ps-subjects span.on {
  background: var(--brand);
  border-color: var(--brand);
  color: #fff;
}

.ps-card {
  border-radius: 12px;
  background: #ffffff;
  border: 1px solid #e1e6e1;
  padding: 14px;
  margin-top: 10px;
}

.ps-card-label {
  margin: 0 0 4px;
  color: var(--brand);
  font-size: 11px;
  font-weight: 700;
}

.ps-card-title {
  margin: 0 0 4px;
  font-size: 14px;
  font-weight: 700;
}

.ps-card-line {
  margin: 0;
  color: var(--muted);
  font-size: 12px;
}

.ps-card-sm {
  margin-top: 10px;
}

.preview-copy h2 {
  margin: 0 0 16px;
  font-size: 30px;
  line-height: 1.3;
}

.check-list {
  margin: 0 0 24px;
  padding: 0;
  list-style: none;
}

.check-list li {
  position: relative;
  padding: 8px 0 8px 28px;
  color: var(--muted);
}

.check-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 15px;
  width: 16px;
  height: 9px;
  border-left: 3px solid var(--brand);
  border-bottom: 3px solid var(--brand);
  transform: rotate(-45deg);
}

.faq-list {
  display: grid;
  gap: 10px;
}

.faq-item {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.faq-item summary {
  cursor: pointer;
  padding: 16px 18px;
  font-weight: 700;
  list-style: none;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  float: right;
  color: var(--brand);
  font-size: 20px;
  line-height: 1;
}

.faq-item[open] summary::after {
  content: "−";
}

.faq-body {
  padding: 0 18px 16px;
  color: var(--muted);
  font-size: 14px;
}

.faq-body p {
  margin: 0;
}

.cta {
  padding: 72px 20px;
  background: var(--brand-dark);
  color: #fff;
  text-align: center;
}

.cta-inner h2 {
  margin: 0 0 8px;
  font-size: 28px;
}

.cta-inner p {
  margin: 0 0 22px;
  color: #cfe4dc;
}

.footer {
  padding: 34px 20px;
  background: #101b18;
  color: #b9c6c1;
  font-size: 13px;
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 10px;
}

.footer p {
  margin: 0;
}

.modal[hidden] {
  display: none;
}

.modal {
  position: fixed;
  inset: 0;
  z-index: 40;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(10, 20, 17, 0.62);
}

.modal-card {
  position: relative;
  width: 100%;
  max-width: 340px;
  background: var(--surface);
  border-radius: var(--radius);
  padding: 26px;
  text-align: center;
}

.modal-card h3 {
  margin: 0 0 6px;
}

.modal-close {
  position: absolute;
  top: 10px;
  right: 12px;
  border: 0;
  background: transparent;
  color: var(--muted);
  font-size: 22px;
  cursor: pointer;
  width: 32px;
  height: 32px;
  line-height: 1;
}

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

.qr-placeholder {
  width: 180px;
  height: 180px;
  margin: 18px auto;
  border-radius: 12px;
  background:
    repeating-linear-gradient(0deg, #17221f 0 8px, #fff 8px 16px),
    repeating-linear-gradient(90deg, #17221f 0 8px, #fff 8px 16px);
  background-blend-mode: difference;
  border: 1px solid var(--line);
}

.reveal {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity 0.45s ease, transform 0.45s ease;
}

.reveal.visible {
  opacity: 1;
  transform: none;
}

@media (max-width: 920px) {
  .subject-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .feature-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .preview-wrap {
    grid-template-columns: 1fr;
    gap: 34px;
  }
}

@media (max-width: 620px) {
  .hero {
    min-height: 72vh;
    padding: 70px 18px 80px;
  }

  .hero h1 {
    font-size: 44px;
  }

  .nav {
    display: none;
  }

  .band {
    padding: 52px 16px;
  }

  .subject-grid,
  .feature-grid {
    grid-template-columns: 1fr;
  }

  .section-head h2,
  .preview-copy h2 {
    font-size: 24px;
  }

  .phone {
    width: 280px;
  }
}