/* 语境官网落地页（第三十轮）。与 App 同一套视觉：纸色底、靛蓝主色、暖色点缀（client/DESIGN.md）。 */
:root {
  --primary: #3b4cca;
  --primary-deep: #26318a;
  --primary-soft: #eceefc;
  --accent: #f2a93b;
  --success: #2e9e6b;
  --error: #d9534a;
  --text: #1a1c23;
  --text-2: #575b66;
  --text-3: #6e727d;
  --paper: #f7f6f3;
  --sunken: #f2f1ee;
  --surface: #ffffff;
  --line: #eceae5;
  --radius: 20px;
  --max: 1160px;
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
    "Noto Sans SC", "Segoe UI", Roboto, sans-serif;
  color: var(--text);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; line-height: 1.6; }
a { color: inherit; text-decoration: none; }
img, svg { display: block; }
.wrap { max-width: var(--max); margin: 0 auto; padding: 0 24px; }
section { padding: 88px 0; scroll-margin-top: 72px; }
h1, h2, h3 { margin: 0; line-height: 1.25; letter-spacing: -0.01em; }
p { margin: 0; }

/* ---------- 顶栏 ---------- */
.nav {
  position: sticky; top: 0; z-index: 10;
  background: rgba(247, 246, 243, 0.86);
  backdrop-filter: saturate(160%) blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s;
}
.nav.scrolled { border-bottom-color: var(--line); }
.nav .wrap { display: flex; align-items: center; height: 68px; gap: 28px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 19px; }
.brand small { display: block; font-size: 12px; font-weight: 400; color: var(--text-3); line-height: 1.2; }
.links { display: flex; gap: 24px; margin-left: 12px; font-size: 15px; color: var(--text-2); }
.links a:hover { color: var(--primary); }
.nav .right { margin-left: auto; display: flex; align-items: center; gap: 12px; }
.lang { display: flex; border: 1px solid var(--line); border-radius: 999px; padding: 3px; background: var(--surface); }
.lang a { padding: 4px 11px; border-radius: 999px; font-size: 13px; color: var(--text-3); }
.lang a.on { background: var(--primary-soft); color: var(--primary); font-weight: 600; }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  height: 46px; padding: 0 22px; border-radius: 14px; font-size: 15px; font-weight: 600;
  border: 1px solid transparent; cursor: pointer; transition: transform 0.15s, background 0.15s, box-shadow 0.15s;
  white-space: nowrap;
}
.btn:hover { transform: translateY(-1px); }
.btn.primary { background: var(--primary); color: #fff; box-shadow: 0 8px 20px rgba(59, 76, 202, 0.25); }
.btn.primary:hover { background: #3240b4; }
.btn.ghost { background: var(--surface); color: var(--text); border-color: var(--line); }
.btn.ghost:hover { border-color: #dad7d0; }
.btn.small { height: 38px; padding: 0 16px; font-size: 14px; border-radius: 12px; }
.btn.lg { height: 54px; padding: 0 28px; font-size: 16px; }

/* ---------- 首屏 ---------- */
.hero { padding: 72px 0 56px; }
.hero-grid { display: grid; grid-template-columns: 1.05fr 0.95fr; gap: 56px; align-items: center; }
.eyebrow { display: inline-flex; align-items: center; gap: 8px; color: var(--primary); font-weight: 600; font-size: 15px; }
.eyebrow::before { content: ""; width: 8px; height: 8px; border-radius: 2px; background: var(--accent); }
.hero h1 { font-size: 56px; margin: 18px 0 20px; font-weight: 800; }
.hero h1 em { font-style: normal; color: var(--primary); }
.hero .sub { font-size: 18px; color: var(--text-2); max-width: 560px; }
.cta-row { display: flex; gap: 14px; margin-top: 34px; flex-wrap: wrap; }
.note { margin-top: 14px; font-size: 13px; color: var(--text-3); }
.note[hidden] { display: none; }

/* 首屏右侧：一课的样子（示意） */
.mock { position: relative; }
.mock .card {
  background: var(--surface); border-radius: 24px; padding: 22px 22px 18px;
  box-shadow: 0 30px 60px rgba(26, 28, 35, 0.10), 0 2px 6px rgba(26, 28, 35, 0.05);
}
.mock .tag { display: inline-block; font-size: 12px; font-weight: 600; color: var(--primary);
  background: var(--primary-soft); padding: 3px 10px; border-radius: 999px; }
.mock h3 { font-size: 19px; margin: 12px 0 2px; }
.mock .en-title { color: var(--text-3); font-size: 13px; margin-bottom: 14px; }
.bubble { max-width: 86%; padding: 10px 14px; border-radius: 16px; margin-bottom: 10px; font-size: 14px; }
.bubble .who { font-size: 11px; color: var(--text-3); margin-bottom: 2px; }
.bubble .zh { font-size: 12px; color: var(--text-3); margin-top: 3px; }
.bubble.them { background: var(--sunken); border-top-left-radius: 4px; }
.bubble.you { background: var(--primary-soft); margin-left: auto; border-top-right-radius: 4px; }
.bubble u { text-decoration-color: var(--primary); text-underline-offset: 3px; color: var(--primary); }
.compare { margin-top: 14px; border-top: 1px dashed var(--line); padding-top: 12px; font-size: 13px; }
.compare div { display: flex; gap: 8px; align-items: flex-start; margin-top: 4px; }
.compare .x { color: var(--error); text-decoration: line-through; opacity: 0.8; }
.compare .ok { color: var(--text); font-weight: 600; }
.mock .float {
  position: absolute; right: -16px; top: -26px; background: var(--surface); border-radius: 16px;
  padding: 12px 16px; box-shadow: 0 16px 36px rgba(26, 28, 35, 0.12); font-size: 13px; min-width: 190px;
}
.mock .float b { display: block; font-size: 14px; margin-bottom: 6px; }
.bar { height: 6px; border-radius: 6px; background: var(--primary-soft); overflow: hidden; }
.bar i { display: block; height: 100%; width: 60%; background: var(--primary); border-radius: 6px; }

.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin-top: 64px; }
.stat { background: var(--surface); border: 1px solid var(--line); border-radius: 18px; padding: 18px 20px; }
.stat b { display: block; font-size: 26px; color: var(--primary); letter-spacing: -0.02em; }
.stat span { font-size: 14px; color: var(--text-2); }

/* ---------- 通用区块 ---------- */
.head { text-align: center; max-width: 720px; margin: 0 auto 48px; }
.head h2 { font-size: 36px; font-weight: 800; }
.head p { margin-top: 12px; color: var(--text-2); font-size: 17px; }
.white { background: var(--surface); }

/* 背景 */
.about { display: grid; grid-template-columns: 1fr 1fr; gap: 56px; align-items: center; }
.about h2 { font-size: 34px; font-weight: 800; margin-bottom: 18px; }
.about p { color: var(--text-2); font-size: 17px; margin-bottom: 14px; }
.pillars { display: grid; gap: 14px; }
.pillar { display: flex; gap: 16px; background: var(--paper); border-radius: 18px; padding: 18px 20px; }
.pillar .n { flex: none; width: 36px; height: 36px; border-radius: 10px; display: grid; place-items: center;
  background: var(--primary); color: #fff; font-weight: 700; }
.pillar h3 { font-size: 17px; margin-bottom: 4px; }
.pillar p { font-size: 14px; margin: 0; }

/* 功能 */
.grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.feature { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 26px; }
.feature .ic { width: 46px; height: 46px; border-radius: 14px; display: grid; place-items: center;
  background: var(--primary-soft); color: var(--primary); margin-bottom: 16px; }
.feature h3 { font-size: 18px; margin-bottom: 8px; }
.feature p { color: var(--text-2); font-size: 15px; }

/* 怎么学 */
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; counter-reset: step; }
.step { position: relative; background: var(--paper); border-radius: var(--radius); padding: 28px 26px; }
.step::before { counter-increment: step; content: counter(step); display: grid; place-items: center;
  width: 34px; height: 34px; border-radius: 50%; background: var(--surface); color: var(--primary);
  font-weight: 800; margin-bottom: 14px; box-shadow: 0 2px 8px rgba(26, 28, 35, 0.08); }
.step h3 { font-size: 18px; margin-bottom: 8px; }
.step p { color: var(--text-2); font-size: 15px; }

/* 价格 */
.plans { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; align-items: stretch; }
.plan { display: flex; flex-direction: column; background: var(--surface); border: 1px solid var(--line);
  border-radius: 24px; padding: 28px; position: relative; }
.plan.hot { border: 2px solid var(--primary); box-shadow: 0 20px 44px rgba(59, 76, 202, 0.14); }
.plan .badge { position: absolute; top: -12px; left: 28px; background: var(--primary); color: #fff;
  font-size: 12px; font-weight: 700; padding: 3px 12px; border-radius: 999px; }
.plan h3 { font-size: 20px; }
.plan .desc { color: var(--text-3); font-size: 14px; margin-top: 4px; min-height: 22px; }
.price { margin: 20px 0 4px; display: flex; align-items: baseline; gap: 6px; flex-wrap: wrap; }
.price b { font-size: 44px; letter-spacing: -0.03em; }
.price s { color: var(--text-3); font-size: 16px; }
.price span { color: var(--text-3); font-size: 15px; }
.plan .extra { color: var(--success); font-size: 14px; font-weight: 600; min-height: 22px; }
.plan ul { list-style: none; padding: 0; margin: 20px 0 26px; flex: 1; }
.plan li { position: relative; padding-left: 26px; margin-bottom: 10px; font-size: 15px; color: var(--text-2); }
.plan li::before { content: ""; position: absolute; left: 2px; top: 6px; width: 12px; height: 7px;
  border-left: 2px solid var(--success); border-bottom: 2px solid var(--success); transform: rotate(-45deg); }
.plan .btn { width: 100%; }
.pricing-note { text-align: center; color: var(--text-3); font-size: 14px; margin-top: 22px; }

/* 常见问题 */
.faq { max-width: 820px; margin: 0 auto; }
.faq details { background: var(--surface); border: 1px solid var(--line); border-radius: 16px;
  padding: 0 22px; margin-bottom: 12px; }
.faq summary { cursor: pointer; list-style: none; padding: 18px 0; font-weight: 600; font-size: 16px;
  display: flex; justify-content: space-between; gap: 16px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--primary); font-size: 22px; line-height: 1; }
.faq details[open] summary::after { content: "−"; }
.faq details p { padding: 0 0 18px; color: var(--text-2); font-size: 15px; }

/* 下载 */
.downloads { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.dl { background: var(--paper); border-radius: var(--radius); padding: 26px; display: flex; flex-direction: column; gap: 6px; }
.dl .ic { width: 46px; height: 46px; border-radius: 14px; background: var(--surface); display: grid; place-items: center;
  color: var(--text); margin-bottom: 10px; }
.dl h3 { font-size: 18px; }
.dl p { color: var(--text-2); font-size: 14px; flex: 1; }
.dl .soon { align-self: flex-start; margin-top: 12px; font-size: 13px; font-weight: 600; color: var(--text-3);
  background: var(--surface); border: 1px dashed #dad7d0; padding: 6px 12px; border-radius: 10px; }
.dl .btn.primary { margin-top: 12px; align-self: flex-start; }
.dl .meta { color: var(--text-3); font-size: 12.5px; margin-top: 6px; }
[hidden] { display: none !important; }
.dl-qr { margin-top: 22px; display: flex; align-items: center; gap: 18px; background: var(--paper);
  border-radius: var(--radius); padding: 18px 22px; }
.dl-qr img { background: #fff; border-radius: 10px; padding: 6px; flex: none; }
.dl-qr p { color: var(--text-2); font-size: 15px; }
.dl.web { background: var(--primary); color: #fff; }
.dl.web p { color: rgba(255, 255, 255, 0.85); }
.dl.web .ic { background: rgba(255, 255, 255, 0.16); color: #fff; }
.dl.web .btn { margin-top: 12px; align-self: flex-start; background: #fff; color: var(--primary); }
.dl .url { font-weight: 700; color: #fff; }

/* 收尾 */
.final { text-align: center; background: linear-gradient(135deg, var(--primary) 0%, var(--primary-deep) 100%);
  color: #fff; border-radius: 28px; padding: 64px 24px; }
.final h2 { font-size: 36px; font-weight: 800; }
.final p { margin-top: 10px; color: rgba(255, 255, 255, 0.85); font-size: 17px; }
.final .cta-row { justify-content: center; }
.final .btn.primary { background: #fff; color: var(--primary); box-shadow: none; }
.final .btn.ghost { background: transparent; color: #fff; border-color: rgba(255, 255, 255, 0.4); }

footer { padding: 40px 0 56px; color: var(--text-3); font-size: 14px; }
footer .wrap { display: flex; flex-wrap: wrap; gap: 16px 28px; align-items: center; }
footer .links2 { display: flex; gap: 20px; margin-left: auto; }
footer a:hover { color: var(--primary); }

/* ---------- 窄屏 ---------- */
@media (max-width: 980px) {
  .links { display: none; }
  .hero-grid, .about { grid-template-columns: 1fr; }
  .hero h1 { font-size: 42px; }
  .grid, .steps, .plans, .downloads { grid-template-columns: 1fr 1fr; }
  .stats { grid-template-columns: 1fr 1fr; }
  .mock { margin-top: 24px; }
  .mock .float { right: 8px; }
}
@media (max-width: 640px) {
  section { padding: 64px 0; }
  .wrap { padding: 0 18px; }
  .nav .wrap { gap: 12px; }
  .brand small, .nav .login { display: none; }
  .hero { padding-top: 40px; }
  .hero h1 { font-size: 34px; }
  .hero .sub { font-size: 16px; }
  .grid, .steps, .plans, .downloads { grid-template-columns: 1fr; }
  .head h2, .about h2, .final h2 { font-size: 28px; }
  .cta-row .btn { flex: 1; }
  .mock .float { position: static; margin-top: 12px; }
  .dl-qr { display: none; } /* 已经在手机上了，不用扫码 */
}