:root {
  --bg: #F8F6F4;
  --bg-alt: #F0ECE6;
  --surface: #FFFFFF;
  --ink: #1C1917;
  --ink-2: #57534E;
  --ink-3: #A8A29E;
  --brand: #D93A3A;
  --brand-soft: #FCECEC;
  --line: #E7E5E4;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg);
  color: var(--ink);
  line-height: 1.8;
  font-size: 15px;
  -webkit-font-smoothing: antialiased;
}

a { text-decoration: none; color: inherit; }
ul { list-style: none; }
img { display: block; max-width: 100%; }

.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 20px;
}

section {
  padding: 88px 0;
}

/* 00 · 服务条 */
.top-bar {
  background-color: var(--ink);
  color: rgba(255, 255, 255, 0.84);
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12.5px;
  gap: 8px;
}
.badge-18 {
  border: 1px solid rgba(255, 255, 255, 0.4);
  color: #fff;
  font-size: 11px;
  padding: 0 4px;
  border-radius: 4px;
  line-height: 1.4;
}

/* 01 · 导航 */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(248, 246, 244, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  font-size: 20px;
  letter-spacing: -0.5px;
}
.brand img {
  height: 32px;
  width: auto;
  border-radius: 6px;
}
.nav-links {
  display: flex;
  gap: 24px;
  font-size: 14px;
  font-weight: 500;
  color: var(--ink-2);
}
.nav-links a:hover { color: var(--ink); }
.btn-primary {
  background-color: var(--brand);
  color: #fff;
  padding: 8px 20px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 600;
  transition: opacity 0.2s;
}
.btn-primary:hover { opacity: 0.9; }
.menu-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 24px;
  color: var(--ink);
  cursor: pointer;
}

/* 02 · 首屏 */
.hero {
  display: grid;
  grid-template-columns: 1.05fr 1fr;
  gap: 60px;
  align-items: center;
  padding: 88px 0;
}
.hero-label {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--ink-3);
  margin-bottom: 16px;
  font-weight: 600;
}
.hero h1 {
  font-size: clamp(36px, 4vw, 58px);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  letter-spacing: -1px;
}
.hero-lead {
  font-size: 20px;
  font-weight: 500;
  font-style: italic;
  color: var(--ink-2);
  margin-bottom: 20px;
}
.hero-desc {
  font-size: 15px;
  line-height: 1.85;
  color: var(--ink-2);
  margin-bottom: 32px;
  max-width: 85%;
}
.hero-actions {
  display: flex;
  gap: 16px;
  margin-bottom: 32px;
}
.btn-large {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 48px;
  padding: 0 28px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
}
.btn-outline {
  border: 1px solid var(--line);
  color: var(--ink);
  transition: border-color 0.2s;
}
.btn-outline:hover { border-color: var(--brand); }
.hero-tags {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  max-width: 400px;
}
.tag-pill {
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 6px 16px;
  font-size: 13px;
  color: var(--ink-2);
  text-align: center;
}
.hero-visual {
  position: relative;
  width: 100%;
  aspect-ratio: 3 / 4;
  display: flex;
  align-items: center;
  justify-content: center;
}
.stack {
  position: relative;
  width: 100%;
  height: 100%;
}
.stack-img {
  position: absolute;
  border: 1px solid rgba(255,255,255,0.8);
  border-radius: 12px;
  box-shadow: 0 12px 32px rgba(0,0,0,0.1);
  overflow: hidden;
}
.stack-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: 50% 22%;
}
.stack-main {
  width: 64%;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 2;
  aspect-ratio: 3 / 4;
}
.stack-left {
  width: 32%;
  top: -5%;
  left: 0;
  transform: rotate(-3deg);
  z-index: 1;
  aspect-ratio: 3 / 4;
}
.stack-right {
  width: 32%;
  bottom: -5%;
  right: 0;
  transform: rotate(3deg);
  z-index: 3;
  aspect-ratio: 3 / 4;
}
.stack-img::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 42%, rgba(0,0,0,.5));
}

/* 03 · 双引擎 */
.dual-engine {
  display: flex;
  align-items: stretch;
  gap: 0;
  background-color: var(--surface);
  border: 1px solid var(--line);
  border-radius: 20px;
  overflow: hidden;
}
.engine-col {
  flex: 1;
  padding: 40px;
  background-color: var(--bg-alt);
}
.engine-col:first-child {
  border-right: 1px dashed var(--ink-3);
}
.engine-slogan {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 24px;
}
.engine-feature {
  margin-bottom: 20px;
}
.engine-feature:last-child { margin-bottom: 0; }
.feature-label {
  font-size: 12px;
  color: var(--brand);
  display: block;
  margin-bottom: 4px;
  font-weight: 600;
}
.feature-text {
  font-size: 14px;
  color: var(--ink-2);
}

/* 04 · 内容线 */
.content-lines {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.line-card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 28px;
  transition: transform 0.2s, border-color 0.2s;
  display: flex;
  flex-direction: column;
}
.line-card:hover {
  transform: translateY(-2px);
  border-color: var(--brand);
}
.line-icon {
  width: 24px;
  height: 24px;
  margin-bottom: 16px;
  color: var(--brand);
}
.line-name {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 8px;
}
.line-target {
  font-size: 13px;
  color: var(--ink-2);
  margin-bottom: 24px;
  flex: 1;
}
.line-link {
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
  display: flex;
  align-items: center;
  gap: 4px;
}

/* 05 · 题材墙 */
.genre-wall {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border: 1px solid var(--line);
  background: var(--surface);
}
.genre-item {
  padding: 22px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  transition: background-color 0.2s;
  cursor: pointer;
}
.genre-item:hover { background-color: var(--brand-soft); }
.genre-item:nth-child(4n) { border-right: none; }
.genre-item:nth-last-child(-n+4) { border-bottom: none; }
.genre-name {
  font-size: 15px;
  font-weight: 600;
}
.genre-arrow {
  font-size: 14px;
  color: var(--ink-3);
}

/* 06 · 排名轨道 */
.section-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  margin-bottom: 32px;
}
.section-title {
  font-size: 24px;
  font-weight: 800;
}
.view-all {
  font-size: 14px;
  font-weight: 600;
  color: var(--brand);
}
.rank-track {
  display: flex;
  gap: 20px;
}
.rank-item {
  flex: 1;
  display: flex;
  flex-direction: column;
}
.rank-num {
  font-size: 40px;
  font-weight: 800;
  color: var(--brand);
  font-variant-numeric: tabular-nums;
  line-height: 1;
  margin-bottom: 12px;
  opacity: 0.9;
}
.rank-cover {
  width: 100%;
  aspect-ratio: 3 / 4;
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 12px;
  position: relative;
}
.rank-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: 50% 22%;
}
.rank-title {
  font-size: 13.5px;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 4px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.rank-ep {
  font-size: 12px;
  color: var(--ink-2);
}

/* 07 · 专题片单 */
.collection-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}
.collection-card {
  display: block;
  cursor: pointer;
}
.collection-cover {
  width: 100%;
  aspect-ratio: 3 / 4;
  border-radius: 12px;
  overflow: hidden;
  margin-bottom: 16px;
  position: relative;
}
.collection-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: 50% 22%;
  transition: transform 0.3s;
}
.collection-card:hover .collection-cover img {
  transform: scale(1.03);
}
.collection-theme {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--brand);
  font-weight: 700;
  margin-bottom: 6px;
}
.collection-name {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 4px;
}
.collection-fit {
  font-size: 12.5px;
  color: var(--ink-2);
}

/* 08 · 安装区 */
.install-section {
  background-color: var(--bg-alt);
  border-radius: 24px;
  padding: 56px;
  text-align: center;
  margin: 0 auto;
  max-width: 900px;
}
.install-title {
  font-size: 28px;
  font-weight: 700;
  line-height: 1.4;
  margin-bottom: 16px;
}
.install-desc {
  font-size: 15px;
  color: var(--ink-2);
  margin-bottom: 32px;
}
.install-action {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 32px;
  margin-bottom: 24px;
}
.btn-download {
  background-color: var(--brand);
  color: #fff;
  height: 48px;
  padding: 0 32px;
  border-radius: 999px;
  font-size: 16px;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.qr-box {
  width: 120px;
  height: 120px;
  background: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 8px;
}
.qr-box img {
  width: 100%;
  height: 100%;
  object-fit: contain;
}
.version-info {
  font-size: 12px;
  color: var(--ink-3);
}

/* 09 · 答疑区 */
.faq-list {
  max-width: 800px;
  margin: 0 auto;
  border-top: 1px solid var(--line);
}
details {
  border-bottom: 1px solid var(--line);
  padding: 20px 0;
}
summary {
  display: flex;
  align-items: center;
  cursor: pointer;
  list-style: none;
}
summary::-webkit-details-marker { display: none; }
.faq-num {
  font-size: 12px;
  color: var(--ink-3);
  font-variant-numeric: tabular-nums;
  width: 42px;
  flex-shrink: 0;
}
.faq-q {
  font-size: 15px;
  font-weight: 600;
  flex: 1;
}
.faq-icon {
  position: relative;
  width: 22px;
  height: 22px;
}
.faq-icon::before,
.faq-icon::after {
  content: '';
  position: absolute;
  background-color: var(--ink);
  transition: transform 0.3s;
}
.faq-icon::before {
  top: 10px; left: 4px; width: 14px; height: 2px;
}
.faq-icon::after {
  top: 4px; left: 10px; width: 2px; height: 14px;
}
details[open] .faq-icon::after {
  transform: rotate(90deg);
  opacity: 0;
}
.faq-a {
  font-size: 13.5px;
  line-height: 1.85;
  color: var(--ink-2);
  padding-left: 42px;
  padding-top: 12px;
}

/* 10 · 页脚 */
.footer {
  padding: 88px 0 40px;
  border-top: 1px solid var(--line);
}
.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 48px;
}
.footer-brand-wrap {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.footer-brand {
  font-size: 20px;
  font-weight: 800;
}
.footer-slogan {
  font-size: 14px;
  color: var(--ink-2);
}
.back-to-top {
  font-size: 14px;
  font-weight: 600;
  color: var(--ink-2);
}
.footer-links {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 32px;
}
.footer-link-row {
  font-size: 14px;
  color: var(--ink-2);
}
.footer-link-row a:hover { color: var(--ink); }
.footer-link-row span { margin: 0 8px; color: var(--ink-3); }
.footer-bottom {
  font-size: 12px;
  color: var(--ink-3);
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: center;
}

/* 吸底条 */
.bottom-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--surface);
  border-top: 1px solid var(--line);
  padding: 12px 20px;
  padding-bottom: calc(12px + env(safe-area-inset-bottom));
  display: none;
  justify-content: space-between;
  align-items: center;
  z-index: 99;
  font-size: 13px;
  font-weight: 600;
}

/* 响应式 */
@media (max-width: 1024px) {
  .hero { gap: 40px; }
  .install-section { padding: 40px 24px; }
}

@media (max-width: 900px) {
  .hero { grid-template-columns: 1fr; }
  .hero-visual { margin-top: 40px; aspect-ratio: 3/4; max-width: 400px; margin-left: auto; margin-right: auto; }
  .stack-left, .stack-right { display: none; }
  .stack-main { width: 100%; }
  .dual-engine { flex-direction: column; }
  .engine-col:first-child { border-right: none; border-bottom: 1px dashed var(--ink-3); }
  .content-lines { grid-template-columns: 1fr; }
  .collection-grid { grid-template-columns: 1fr; gap: 32px; }
}

@media (max-width: 768px) {
  section { padding: 52px 0; }
  .nav-links { display: none; }
  .menu-toggle { display: block; }
  .hero h1 { font-size: 36px; }
  .hero-desc { max-width: 100%; }
  .hero-tags { grid-template-columns: 1fr; }
  .genre-wall { grid-template-columns: repeat(2, 1fr); }
  .genre-item:nth-child(4n) { border-right: 1px solid var(--line); }
  .genre-item:nth-child(2n) { border-right: none; }
  .genre-item:nth-last-child(-n+4) { border-bottom: 1px solid var(--line); }
  .genre-item:nth-last-child(-n+2) { border-bottom: none; }
  .rank-track { overflow-x: auto; scroll-snap-type: x mandatory; padding-bottom: 16px; }
  .rank-item { min-width: 44vw; scroll-snap-align: start; }
  .collection-grid { display: flex; overflow-x: auto; scroll-snap-type: x mandatory; gap: 16px; padding-bottom: 16px; }
  .collection-card { min-width: 62vw; scroll-snap-align: start; }
  .install-action { flex-direction: column; }
  .footer-top { flex-direction: column; gap: 24px; }
  .bottom-bar { display: flex; }
  .footer { padding-bottom: 100px; }
}