:root {
  --brand: #2f6fed;
  --brand-dark: #1d4fbf;
  --brand-soft: #eef3ff;
  --ink: #101828;
  --ink-2: #344054;
  --muted: #667085;
  --bg: #f6f8fd;
  --card: #fff;
  --line: #e6ebf5;
  --green: #12925a;
  --radius: 18px;
  --shadow-sm: 0 2px 8px rgba(16, 24, 40, .04);
  --shadow-md: 0 14px 34px rgba(16, 24, 40, .07);
  --shadow-lg: 0 30px 70px rgba(16, 24, 40, .14);
  --nav-h: 68px;
}

* { box-sizing: border-box; }
html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 16px);
  -webkit-text-size-adjust: 100%;
}
body {
  margin: 0;
  background:
    radial-gradient(900px 480px at 12% -6%, #e4edff 0, transparent 60%),
    radial-gradient(760px 420px at 92% 2%, #eaf7f1 0, transparent 55%),
    var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; }
:focus-visible { outline: 2px solid var(--brand); outline-offset: 3px; border-radius: 6px; }

/* ---------- 顶部导航 ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  height: var(--nav-h);
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  gap: 26px;
  background: rgba(246, 248, 253, .78);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  transition: box-shadow .25s, background .25s;
}
.nav.is-scrolled {
  background: rgba(255, 255, 255, .92);
  box-shadow: 0 1px 0 var(--line), 0 10px 30px rgba(16, 24, 40, .05);
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 17px; letter-spacing: .2px; }
.brand img { width: 32px; height: 32px; border-radius: 9px; box-shadow: 0 6px 16px rgba(47, 111, 237, .28); }
.nav-links { display: flex; gap: 6px; margin-left: auto; color: var(--ink-2); font-size: 14px; }
.nav-links a { padding: 8px 12px; border-radius: 9px; transition: background .18s, color .18s; }
.nav-links a:hover { color: var(--brand); background: var(--brand-soft); }
.nav-admin {
  padding: 8px 16px;
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 14px;
  background: #fff;
  box-shadow: var(--shadow-sm);
  transition: .18s;
}
.nav-admin:hover { border-color: var(--brand); color: var(--brand); transform: translateY(-1px); }
.nav-toggle {
  display: none;
  width: 40px;
  height: 40px;
  margin-left: auto;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fff;
  cursor: pointer;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 4px;
  padding: 0;
}
.nav-toggle span { display: block; width: 17px; height: 2px; border-radius: 2px; background: var(--ink-2); transition: .2s; }
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }
.nav-mobile {
  position: absolute;
  top: calc(var(--nav-h) - 6px);
  left: 12px;
  right: 12px;
  padding: 10px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 16px;
  box-shadow: var(--shadow-md);
  display: none;
  flex-direction: column;
  gap: 2px;
}
.nav-mobile.open { display: flex; }
.nav-mobile a { padding: 12px 14px; border-radius: 10px; font-size: 15px; color: var(--ink-2); }
.nav-mobile a:active { background: var(--brand-soft); color: var(--brand); }
.nav-mobile .nav-mobile-login { margin-top: 6px; background: var(--brand); color: #fff; text-align: center; font-weight: 600; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 50px;
  padding: 0 24px;
  border-radius: 13px;
  font-weight: 600;
  font-size: 15px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform .18s, box-shadow .18s, border-color .18s, color .18s;
  -webkit-tap-highlight-color: transparent;
}
.btn:active { transform: scale(.98); }
.btn-primary {
  background: linear-gradient(135deg, var(--brand), var(--brand-dark));
  color: #fff;
  box-shadow: 0 14px 30px rgba(47, 111, 237, .26);
}
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 18px 38px rgba(47, 111, 237, .34); }
.btn-ghost { background: #fff; border-color: var(--line); color: var(--ink); box-shadow: var(--shadow-sm); }
.btn-ghost:hover { border-color: #b9cdf8; color: var(--brand); }

/* ---------- 首屏 ---------- */
.hero {
  max-width: 1180px;
  margin: 0 auto;
  padding: 46px 24px 40px;
  display: grid;
  grid-template-columns: 1.06fr .94fr;
  gap: 48px;
  align-items: center;
}
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--brand);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 1.6px;
}
.eyebrow::before {
  content: "";
  width: 18px;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  opacity: .55;
}
.hero h1 {
  margin: 16px 0 18px;
  font-size: clamp(40px, 5.6vw, 66px);
  line-height: 1.1;
  letter-spacing: -1.5px;
  font-weight: 800;
}
.hero h1 span {
  background: linear-gradient(120deg, #2f6fed 10%, #6d9bff 55%, #33b37e 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.lead { color: var(--muted); font-size: 17px; line-height: 1.85; max-width: 600px; margin: 0; }
.lead strong { color: var(--ink-2); font-weight: 600; }
.hero-actions, .download-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 28px; }
.hero-meta { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 24px; }
.hero-meta span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, .8);
  border: 1px solid var(--line);
  color: var(--ink-2);
  font-size: 12.5px;
}

.hero-visual { position: relative; min-height: 500px; }
.hero-visual::before {
  content: "";
  position: absolute;
  inset: 8% 4% 6%;
  background: radial-gradient(circle at 50% 45%, rgba(47, 111, 237, .16), transparent 68%);
  filter: blur(6px);
  z-index: 0;
}
.phone {
  position: absolute;
  width: 248px;
  height: 468px;
  border-radius: 34px;
  background: #0d1526;
  padding: 13px;
  box-shadow: var(--shadow-lg);
  z-index: 1;
}
.phone::after {
  content: "";
  position: absolute;
  inset: 13px;
  border-radius: 25px;
  background: #f8faff;
}
.phone > * { position: relative; z-index: 1; }
.phone-back { right: 6px; top: 26px; transform: rotate(6deg) scale(.96); opacity: .85; }
.phone-front { left: 34px; top: 0; transform: rotate(-4deg); }
.phone-bar { width: 60px; height: 6px; border-radius: 999px; background: #1f2937; margin: 8px auto 18px; }
.mock-title { font-size: 20px; font-weight: 700; margin: 6px 14px 12px; }
.mock-progress { height: 8px; border-radius: 999px; background: #e9edf5; margin: 0 14px 18px; overflow: hidden; }
.mock-progress i { display: block; height: 100%; background: linear-gradient(90deg, #2f6fed, #6d9bff); }
.mock-row {
  margin: 8px 14px;
  padding: 12px;
  border-radius: 12px;
  background: #fff;
  font-size: 12px;
  display: flex;
  gap: 8px;
  align-items: center;
  box-shadow: 0 6px 16px rgba(31, 41, 55, .05);
}
.mock-row b { color: var(--brand); font-size: 11px; }
.mock-row em { margin-left: auto; color: #98a2b3; font-style: normal; }
.mock-button {
  margin: 20px 14px;
  height: 42px;
  border-radius: 12px;
  background: linear-gradient(135deg, #2f6fed, #1d4fbf);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  font-weight: 600;
}
.mock-chip { display: inline-block; margin: 10px 0 0 24px; padding: 4px 12px; border-radius: 999px; background: #fff4e5; color: #b76e00; font-size: 11px; }
.mock-poem { margin: 24px 20px; font-size: 27px; line-height: 1.9; font-weight: 700; text-align: center; letter-spacing: 1px; }
.mock-hint { margin: 18px 24px; padding: 16px; border: 1px dashed #c7d5ef; border-radius: 12px; color: var(--brand); text-align: center; font-size: 12px; background: #f7f9ff; }
.mock-actions { display: flex; gap: 6px; margin: 18px 18px; }
.mock-actions span { flex: 1; text-align: center; padding: 10px 0; border-radius: 10px; background: #eef3ff; color: var(--brand); font-size: 11px; }

/* ---------- 复习节奏带 ---------- */
.cadence {
  max-width: 1180px;
  margin: 0 auto;
  padding: 8px 24px 20px;
  display: flex;
  align-items: center;
  gap: 18px;
  flex-wrap: wrap;
  justify-content: center;
  color: var(--muted);
  font-size: 13px;
}
.cadence-label { font-weight: 600; color: var(--ink-2); }
.cadence-track { display: flex; align-items: center; gap: 6px; flex-wrap: wrap; }
.cadence-track i {
  font-style: normal;
  padding: 5px 12px;
  border-radius: 999px;
  background: #fff;
  border: 1px solid var(--line);
  box-shadow: var(--shadow-sm);
  color: var(--ink-2);
  font-weight: 600;
  font-size: 12.5px;
}
.cadence-track i:last-child { background: var(--brand); border-color: var(--brand); color: #fff; }

/* ---------- 通用区块 ---------- */
.section { max-width: 1180px; margin: 0 auto; padding: 68px 24px; }
.section-head { text-align: center; margin-bottom: 38px; }
.section-head h2 { margin: 12px 0 0; font-size: clamp(26px, 3.6vw, 38px); letter-spacing: -.8px; line-height: 1.25; }
.section-head .eyebrow { justify-content: center; }
.section-head .eyebrow::before { display: none; }

.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.feature {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 26px;
  box-shadow: var(--shadow-sm);
  transition: transform .22s, box-shadow .22s, border-color .22s;
}
.feature:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); border-color: #d7e2f7; }
.feature-icon {
  width: 46px;
  height: 46px;
  border-radius: 13px;
  background: var(--brand-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 22px;
}
.feature h3 { margin: 16px 0 6px; font-size: 18px; }
.feature p { margin: 0; color: var(--muted); font-size: 14px; line-height: 1.8; }

.screens-section { padding-top: 22px; }
.screen-row { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.screen-card {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  min-height: 172px;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: transform .22s, box-shadow .22s;
}
.screen-card:hover { transform: translateY(-3px); box-shadow: var(--shadow-md); }
.screen-top { background: linear-gradient(135deg, #2f6fed, #1d4fbf); color: #fff; padding: 16px 20px; font-weight: 600; font-size: 15px; }
.screen-body { padding: 18px 20px; color: var(--muted); font-size: 14px; }

.download-section { padding-top: 34px; }
.download-card {
  position: relative;
  overflow: hidden;
  background: linear-gradient(135deg, #111c33, #1e2f57);
  color: #fff;
  border-radius: 26px;
  padding: 50px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 40px;
  box-shadow: 0 34px 70px rgba(17, 28, 51, .28);
}
.download-card::before {
  content: "";
  position: absolute;
  width: 380px;
  height: 380px;
  right: -60px;
  top: -140px;
  background: radial-gradient(circle, rgba(109, 155, 255, .35), transparent 66%);
  pointer-events: none;
}
.download-card h2 { margin: 10px 0 12px; font-size: clamp(28px, 3.4vw, 38px); }
.download-card .eyebrow { color: #9db9ff; }
.download-card .lead { color: rgba(255, 255, 255, .74); }
.download-card .btn-ghost { background: rgba(255, 255, 255, .1); border-color: rgba(255, 255, 255, .26); color: #fff; box-shadow: none; }
.download-card .btn-ghost:hover { background: rgba(255, 255, 255, .16); color: #fff; border-color: rgba(255, 255, 255, .4); }
.download-note { color: rgba(255, 255, 255, .5); font-size: 12.5px; margin-top: 16px; }
.qr-box { text-align: center; position: relative; z-index: 1; }
.qr-placeholder {
  width: 128px; height: 128px; border-radius: 18px;
  background: repeating-linear-gradient(45deg, #fff, #fff 8px, #eef3ff 8px, #eef3ff 16px);
  color: var(--brand-dark); font-weight: 800; font-size: 26px;
  display: flex; align-items: center; justify-content: center;
  margin: 0 auto 10px;
  box-shadow: 0 16px 34px rgba(0, 0, 0, .24);
}
.qr-box .muted { color: rgba(255, 255, 255, .56); font-size: 12px; }

.faq { max-width: 820px; margin: 0 auto; }
.faq details {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 4px 22px;
  margin-bottom: 10px;
  box-shadow: var(--shadow-sm);
  transition: border-color .18s;
}
.faq details[open] { border-color: #c9d9f8; }
.faq summary {
  cursor: pointer;
  font-weight: 600;
  padding: 16px 0;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
  content: "+";
  flex: none;
  width: 24px; height: 24px;
  border-radius: 50%;
  background: var(--brand-soft);
  color: var(--brand);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
  transition: transform .2s;
}
.faq details[open] summary::after { transform: rotate(45deg); }
.faq p { color: var(--muted); margin: 0 0 16px; font-size: 14px; line-height: 1.8; }

/* ---------- 下载页 ---------- */
.download-page { max-width: 780px; padding-top: 40px; }
.download-panel {
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 24px;
  padding: 40px;
  box-shadow: var(--shadow-md);
}
.download-panel h1 { margin: 12px 0 10px; font-size: clamp(28px, 5vw, 38px); letter-spacing: -.6px; }
.download-meta { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 14px; }
.download-meta span {
  padding: 5px 12px;
  border-radius: 999px;
  background: var(--brand-soft);
  color: var(--brand-dark);
  font-size: 12.5px;
  font-weight: 600;
}
.install-steps {
  margin-top: 28px;
  padding: 20px 22px;
  border-radius: 16px;
  background: #f7f9ff;
  border: 1px solid #e3e9f5;
  color: var(--ink-2);
  font-size: 14px;
  line-height: 1.9;
}
.install-steps strong { display: block; margin-bottom: 8px; color: var(--ink); }
.install-steps ol { margin: 0; padding-left: 20px; }
.install-steps li + li { margin-top: 4px; }
.download-tip { margin-top: 22px; color: #98a2b3; font-size: 12.5px; line-height: 1.8; }
.download-back { margin-top: 24px; font-size: 14px; }
.download-back a { color: var(--brand); font-weight: 600; }

/* ---------- 页脚 ---------- */
.footer {
  max-width: 1180px;
  margin: 0 auto;
  padding: 26px 24px 44px;
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 18px;
  color: #8a94a6;
  font-size: 13px;
}
.footer-links { display: flex; gap: 6px; flex-wrap: wrap; }
.footer-links a { padding: 6px 10px; border-radius: 8px; }
.footer-links a:hover { color: var(--brand); background: var(--brand-soft); }

/* ---------- 入场动画 ---------- */
.js .reveal { opacity: 0; transform: translateY(18px); transition: opacity .6s ease, transform .6s ease; }
.js .reveal.in { opacity: 1; transform: none; }
.js .reveal:nth-child(2) { transition-delay: .06s; }
.js .reveal:nth-child(3) { transition-delay: .12s; }
.js .reveal:nth-child(4) { transition-delay: .18s; }
.js .reveal:nth-child(5) { transition-delay: .24s; }
.js .reveal:nth-child(6) { transition-delay: .3s; }

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
  .nav { gap: 14px; }
  .nav-links { display: none; }
  .nav-toggle { display: inline-flex; }
  .nav-admin { display: none; }
  .hero { grid-template-columns: 1fr; padding-top: 26px; gap: 26px; }
  .hero-text { text-align: center; }
  .hero-meta, .hero-actions { justify-content: center; }
  .lead { margin: 0 auto; }
  .hero-visual { min-height: 470px; max-width: 420px; margin: 0 auto; width: 100%; }
  .feature-grid { grid-template-columns: 1fr 1fr; }
  .screen-row { grid-template-columns: 1fr 1fr; }
  .download-card { flex-direction: column; text-align: center; padding: 36px 24px; }
  .download-card .eyebrow { justify-content: center; }
  .download-card .download-actions { justify-content: center; }
  .footer { flex-direction: column; text-align: center; }
}

@media (max-width: 620px) {
  :root { --nav-h: 62px; }
  .nav { padding: 0 16px; }
  .hero { padding: 22px 16px 26px; }
  .hero h1 { font-size: clamp(34px, 10vw, 44px); letter-spacing: -1px; }
  .lead { font-size: 15.5px; }
  .hero-actions .btn { flex: 1 1 180px; }
  .hero-visual { min-height: 400px; max-width: 340px; }
  .phone { width: 198px; height: 374px; border-radius: 28px; padding: 11px; }
  .phone::after { inset: 11px; border-radius: 20px; }
  .phone-front { left: 0; }
  .phone-back { right: 0; top: 22px; }
  .phone-bar { width: 48px; margin-bottom: 12px; }
  .mock-title { font-size: 16px; margin-bottom: 8px; }
  .mock-row { padding: 9px; font-size: 11px; margin: 6px 12px; }
  .mock-button { height: 34px; margin: 12px; }
  .mock-poem { font-size: 21px; margin: 18px 12px; }
  .mock-hint { margin: 12px; padding: 12px; }
  .mock-actions { margin: 14px; }
  .mock-actions span { padding: 8px 0; font-size: 10px; }
  .mock-chip { margin-left: 18px; }
  .section { padding: 48px 16px; }
  .feature-grid, .screen-row { grid-template-columns: 1fr; }
  .cadence { padding-left: 16px; padding-right: 16px; gap: 10px; }
  .download-panel { padding: 26px 18px; }
  .download-panel .download-actions .btn { flex: 1 1 100%; }
  .footer { padding-left: 16px; padding-right: 16px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .js .reveal { opacity: 1; transform: none; }
}