/* 七弦谱落地页样式
 *
 * 用于首页 / —— 静态营销落地页。
 * 与 content.css 共享一套品牌色板（墨黑 / 茶金 / 月白 / 沉茶 / 深灰），
 * 但版式更"营销"：宽幅、卡片、CTA 区、留白更大。
 *
 * 设计参考：Linear / Stripe / Notion 的极简文人风。
 * 不引入任何 Web Font CDN，全部走系统字体栈。
 */

/* ============ 设计 token ============ */
:root {
  /* 品牌色 */
  --ink: #1a1a1a;          /* 墨黑：暗模式背景 / 强调色 */
  --ink-soft: #2d2d35;     /* 深灰：暗模式次背景 */
  --tea-gold: #8a6e3a;     /* 茶金：主强调色 */
  --tea-gold-soft: #c9b78e;/* 沉茶：次要装饰 */
  --moon-white: #f5f0e6;   /* 月白：暗模式主文字 */

  /* 落地页色 token */
  --bg: #fbfaf6;
  --bg-elevated: #ffffff;
  --bg-soft: #f3efe5;
  --fg: #1a1a1a;
  --fg-muted: #5e5a52;
  --fg-soft: #8a8579;
  --border: #e5dfd0;
  --border-strong: #d4cbb4;
  --accent: #8a6e3a;
  --accent-hover: #6f5829;
  --accent-on: #ffffff;
  --link: #1f6fb5;
  --shadow-sm: 0 1px 2px rgba(26, 26, 26, 0.04), 0 1px 3px rgba(26, 26, 26, 0.06);
  --shadow-md: 0 4px 6px rgba(26, 26, 26, 0.04), 0 10px 20px rgba(26, 26, 26, 0.06);
  --shadow-lg: 0 12px 24px rgba(26, 26, 26, 0.08), 0 24px 48px rgba(26, 26, 26, 0.10);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;

  /* 字体栈 */
  --font-serif: 'Noto Serif SC', 'Source Han Serif SC', 'Songti SC',
                'Noto Serif', Georgia, 'Times New Roman', serif;
  --font-sans: 'Noto Sans SC', 'Source Han Sans SC', 'PingFang SC', 'Microsoft YaHei',
               -apple-system, BlinkMacSystemFont, 'Segoe UI', Inter, system-ui,
               'Helvetica Neue', Arial, sans-serif;
}

[data-theme='dark'] {
  --bg: #1a1a1a;
  --bg-elevated: #232228;
  --bg-soft: #2d2d35;
  --fg: #f5f0e6;
  --fg-muted: #b3ad9c;
  --fg-soft: #807a6d;
  --border: #3a3530;
  --border-strong: #524b40;
  --accent: #c9b78e;
  --accent-hover: #d8c8a3;
  --accent-on: #1a1a1a;
  --link: #6fb1ff;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 16px 32px rgba(0, 0, 0, 0.4);
}

/* ============ 基础 ============ */
* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body.landing {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body.landing h1, body.landing h2, body.landing h3 {
  font-family: var(--font-serif);
  font-weight: 700;
  letter-spacing: -0.01em;
  margin: 0;
}

body.landing a { color: inherit; text-decoration: none; }
body.landing img { max-width: 100%; height: auto; display: block; }

.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 24px;
}

.eyebrow {
  font-family: var(--font-serif);
  font-size: 13px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 600;
  margin: 0 0 12px;
}

.section-title {
  font-size: clamp(28px, 4vw, 38px);
  line-height: 1.2;
  margin: 0 0 16px;
}

.section-lead {
  font-size: 17px;
  color: var(--fg-muted);
  max-width: 640px;
  margin: 0 0 48px;
  line-height: 1.7;
}

/* ============ Header ============ */
.lp-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(251, 250, 246, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
}
[data-theme='dark'] .lp-header { background: rgba(26, 26, 26, 0.85); }

.lp-header-inner {
  max-width: 1120px;
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  gap: 28px;
}

.lp-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 17px;
  color: var(--fg);
}
.lp-brand img { width: 26px; height: 26px; }

.lp-nav {
  display: flex;
  gap: 24px;
  align-items: center;
}
.lp-nav a {
  color: var(--fg-muted);
  font-size: 15px;
  transition: color .15s;
}
.lp-nav a:hover { color: var(--fg); }

.lp-spacer { flex: 1; }

.lp-actions { display: flex; align-items: center; gap: 12px; }

/* 主题切换按钮 */
.lp-theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  padding: 0;
  background: transparent;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  color: var(--fg-muted);
  cursor: pointer;
  transition: color .15s, border-color .15s, background .15s;
}
.lp-theme-toggle:hover {
  color: var(--accent);
  border-color: var(--accent);
}
.lp-theme-toggle svg { width: 18px; height: 18px; display: block; }
.lp-theme-toggle .icon-sun { display: none; }
.lp-theme-toggle .icon-moon { display: block; }
[data-theme='dark'] .lp-theme-toggle .icon-sun { display: block; }
[data-theme='dark'] .lp-theme-toggle .icon-moon { display: none; }

/* 主 CTA 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 20px;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 500;
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  transition: background .15s, border-color .15s, color .15s, transform .1s;
  white-space: nowrap;
  line-height: 1.2;
}
.btn:active { transform: translateY(1px); }

.btn-primary {
  background: var(--accent);
  color: var(--accent-on);
  border-color: var(--accent);
}
.btn-primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); }

.btn-ghost {
  background: transparent;
  color: var(--fg);
  border-color: var(--border-strong);
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

.btn-lg { padding: 14px 26px; font-size: 16px; }

.btn-arrow::after {
  content: "→";
  font-size: 1.05em;
  transition: transform .15s;
}
.btn-arrow:hover::after { transform: translateX(3px); }

/* 移动端菜单切换 */
.lp-menu-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  width: 38px;
  height: 38px;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--fg);
  padding: 0;
}
.lp-menu-toggle svg { width: 18px; height: 18px; }

/* ============ Hero ============ */
.hero {
  padding: 96px 0 80px;
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 60% 50% at 50% 0%,
              rgba(138, 110, 58, 0.10), transparent 70%);
  pointer-events: none;
}
[data-theme='dark'] .hero::before {
  background: radial-gradient(ellipse 60% 50% at 50% 0%,
              rgba(201, 183, 142, 0.08), transparent 70%);
}

.hero-inner {
  position: relative;
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: 1.05fr 1fr;
  gap: 64px;
  align-items: center;
}

.hero-text { min-width: 0; }

.hero h1 {
  font-size: clamp(36px, 5.5vw, 56px);
  line-height: 1.12;
  margin: 0 0 20px;
  letter-spacing: -0.02em;
}
.hero h1 .accent {
  color: var(--accent);
  font-style: italic;
  font-weight: 700;
}

.hero-sub {
  font-size: clamp(16px, 1.6vw, 19px);
  color: var(--fg-muted);
  line-height: 1.65;
  margin: 0 0 36px;
  max-width: 560px;
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-bottom: 28px;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  color: var(--fg-soft);
  font-size: 14px;
}
.hero-meta span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.hero-meta .dot {
  width: 5px; height: 5px;
  border-radius: 50%;
  background: var(--accent);
}

/* Hero 视觉占位 */
.hero-visual {
  position: relative;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  aspect-ratio: 4 / 3;
}
.hero-visual img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.hero-visual::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  box-shadow: inset 0 0 0 1px rgba(255,255,255,0.04);
  pointer-events: none;
}

/* ============ Section 通用 ============ */
section {
  padding: 96px 0;
}

.section-head {
  margin-bottom: 56px;
  max-width: 720px;
}

/* ============ Features ============ */
.features {
  background: var(--bg-soft);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 32px 28px;
  transition: border-color .2s, transform .2s, box-shadow .2s;
}
.feature-card:hover {
  border-color: var(--border-strong);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}
.feature-icon {
  width: 44px; height: 44px;
  border-radius: var(--radius-sm);
  background: rgba(138, 110, 58, 0.10);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  margin-bottom: 18px;
}
[data-theme='dark'] .feature-icon { background: rgba(201, 183, 142, 0.12); }
.feature-icon svg { width: 22px; height: 22px; }
.feature-card h3 {
  font-size: 19px;
  margin: 0 0 8px;
  font-weight: 600;
}
.feature-card p {
  margin: 0;
  color: var(--fg-muted);
  font-size: 15px;
  line-height: 1.6;
}

/* ============ Audience ============ */
.audience-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}
.audience-card {
  padding: 8px 0;
}
.audience-card .audience-icon {
  font-family: var(--font-serif);
  font-size: 28px;
  color: var(--accent);
  margin-bottom: 16px;
  line-height: 1;
  letter-spacing: 0.05em;
}
.audience-card h3 {
  font-size: 21px;
  margin: 0 0 12px;
}
.audience-card p {
  margin: 0;
  color: var(--fg-muted);
  font-size: 15px;
  line-height: 1.7;
}

/* ============ Scores Preview ============ */
.scores {
  background: var(--bg-soft);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}
.scores-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  margin-bottom: 48px;
  flex-wrap: wrap;
  gap: 24px;
}
.scores-head .section-lead { margin: 0; }
.scores-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 20px;
}
.score-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color .2s, transform .2s, box-shadow .2s;
  display: flex;
  flex-direction: column;
}
.score-card:hover {
  border-color: var(--accent);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}
.score-card .cover {
  aspect-ratio: 16 / 10;
  background: var(--bg-soft);
  overflow: hidden;
}
.score-card .cover img {
  width: 100%; height: 100%;
  object-fit: cover;
  transition: transform .4s;
}
.score-card:hover .cover img { transform: scale(1.04); }
.score-card .meta {
  padding: 16px 18px 18px;
}
.score-card .title-zh {
  font-family: var(--font-serif);
  font-size: 19px;
  font-weight: 700;
  margin: 0 0 4px;
  color: var(--fg);
  letter-spacing: 0.02em;
}
.score-card .title-py {
  font-size: 13px;
  color: var(--fg-soft);
  margin: 0;
  font-style: italic;
}
.scores-cta {
  margin-top: 40px;
  text-align: center;
}

/* ============ Culture ============ */
.culture-inner {
  max-width: 760px;
  margin: 0 auto;
  text-align: center;
}
.culture-inner .section-lead { margin: 0 auto; }
.culture-body {
  font-family: var(--font-serif);
  font-size: 17px;
  line-height: 1.85;
  color: var(--fg);
  text-align: left;
  margin-top: 32px;
}
.culture-body p { margin: 0 0 18px; }
.culture-body p:last-child { margin-bottom: 0; }
.culture-body em {
  color: var(--accent);
  font-style: italic;
}

/* ============ FAQ ============ */
.faq {
  background: var(--bg-soft);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}
.faq-list {
  max-width: 800px;
  margin: 0 auto;
}
.faq-item {
  border-bottom: 1px solid var(--border);
  padding: 4px 0;
}
.faq-item summary {
  cursor: pointer;
  list-style: none;
  padding: 22px 56px 22px 8px;
  font-family: var(--font-serif);
  font-size: 18px;
  font-weight: 600;
  position: relative;
  color: var(--fg);
  transition: color .15s;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary:hover { color: var(--accent); }
.faq-item summary::after {
  content: "+";
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-sans);
  font-size: 22px;
  font-weight: 300;
  color: var(--fg-muted);
  transition: transform .2s;
  line-height: 1;
}
.faq-item[open] summary::after {
  transform: translateY(-50%) rotate(45deg);
  color: var(--accent);
}
.faq-answer {
  padding: 0 8px 24px;
  color: var(--fg-muted);
  font-size: 15.5px;
  line-height: 1.75;
}
.faq-answer p { margin: 0 0 12px; }
.faq-answer p:last-child { margin-bottom: 0; }
.faq-answer a {
  color: var(--accent);
  border-bottom: 1px solid currentColor;
}

/* ============ Final CTA ============ */
.final-cta {
  background: var(--ink);
  color: var(--moon-white);
  text-align: center;
  padding: 96px 24px;
  border-top: 1px solid var(--border);
}
[data-theme='dark'] .final-cta {
  background: var(--ink-soft);
  border-top: 1px solid var(--border);
}
.final-cta h2 {
  font-size: clamp(30px, 4vw, 44px);
  color: var(--moon-white);
  margin: 0 0 16px;
  line-height: 1.2;
}
.final-cta p {
  color: var(--tea-gold-soft);
  font-size: 17px;
  margin: 0 0 36px;
  max-width: 540px;
  margin-left: auto;
  margin-right: auto;
}
.final-cta .btn-primary {
  background: var(--tea-gold-soft);
  color: var(--ink);
  border-color: var(--tea-gold-soft);
}
.final-cta .btn-primary:hover {
  background: var(--moon-white);
  border-color: var(--moon-white);
  color: var(--ink);
}

/* ============ Footer ============ */
.lp-footer {
  background: var(--bg);
  padding: 56px 24px 40px;
  border-top: 1px solid var(--border);
  font-size: 14px;
  color: var(--fg-muted);
}
.lp-footer-inner {
  max-width: 1120px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.4fr repeat(3, 1fr);
  gap: 48px;
}
.lp-footer-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 17px;
  color: var(--fg);
  margin-bottom: 12px;
}
.lp-footer-brand img { width: 24px; height: 24px; }
.lp-footer-tagline {
  margin: 0 0 16px;
  font-size: 14px;
  color: var(--fg-muted);
  line-height: 1.6;
  max-width: 320px;
}
.lp-footer h4 {
  font-family: var(--font-sans);
  font-size: 13px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--fg-soft);
  font-weight: 600;
  margin: 0 0 14px;
}
.lp-footer ul {
  list-style: none;
  margin: 0;
  padding: 0;
}
.lp-footer li { margin: 0 0 10px; }
.lp-footer a {
  color: var(--fg-muted);
  transition: color .15s;
}
.lp-footer a:hover { color: var(--accent); }
.lp-footer-bottom {
  max-width: 1120px;
  margin: 40px auto 0;
  padding-top: 24px;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
  font-size: 13px;
  color: var(--fg-soft);
}
.lp-footer-langs { display: flex; gap: 14px; }
.lp-footer-langs a {
  color: var(--fg-soft);
}
.lp-footer-langs a:hover { color: var(--accent); }

/* ============ 滚动入场动画 ============ */
@media (prefers-reduced-motion: no-preference) {
  .reveal {
    opacity: 0;
    transform: translateY(16px);
    transition: opacity .6s ease, transform .6s ease;
  }
  .reveal.is-visible {
    opacity: 1;
    transform: none;
  }
}

/* ============ 响应式 ============ */
@media (max-width: 960px) {
  .hero-inner {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .hero-visual { max-width: 560px; margin: 0 auto; width: 100%; }
  .audience-grid { grid-template-columns: 1fr; gap: 36px; }
  .lp-footer-inner { grid-template-columns: 1fr 1fr; gap: 32px; }
}

@media (max-width: 640px) {
  body.landing { font-size: 15px; }
  section { padding: 64px 0; }
  .hero { padding: 56px 0 48px; }
  .hero-cta .btn { flex: 1 1 100%; justify-content: center; }
  .hero-meta { gap: 14px; font-size: 13px; }
  .section-head { margin-bottom: 40px; }
  .section-lead { font-size: 16px; }
  .feature-card { padding: 24px 22px; }
  .scores-head { flex-direction: column; align-items: flex-start; }
  .final-cta { padding: 64px 24px; }
  .lp-footer-inner { grid-template-columns: 1fr; gap: 28px; }
  .lp-footer-bottom { flex-direction: column; align-items: flex-start; }

  /* 移动端导航折叠 */
  .lp-menu-toggle { display: inline-flex; }
  .lp-nav,
  .lp-actions .desktop-only { display: none; }
  .lp-nav.is-open {
    display: flex;
    position: absolute;
    top: 100%;
    left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    background: var(--bg-elevated);
    border-bottom: 1px solid var(--border);
    padding: 12px 24px 16px;
    gap: 6px;
  }
  .lp-nav.is-open a {
    padding: 10px 6px;
    border-radius: var(--radius-sm);
    font-size: 16px;
  }
  .lp-nav.is-open a:hover { background: var(--bg-soft); }
  .lp-header-inner { position: relative; }
}

/* ============ 焦点可达 ============ */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 3px;
}
.btn:focus-visible { outline-offset: 4px; }

/* skip link */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--accent);
  color: var(--accent-on);
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  z-index: 200;
}
.skip-link:focus {
  left: 12px;
  top: 12px;
}