:root {
  --bg: #FCFAF8;
  --bg-alt: #F5F0E8;
  --surface: #FFFFFF;
  --ink: #22211F;
  --ink-2: #5E5A54;
  --ink-3: #99938A;
  --brand: #C93B43;
  --brand-soft: #FCF2F2;
  --line: #E6E0D6;
}
*, *::before, *::after {
  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;
}
img {
  display: block;
  max-width: 100%;
}
.container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0 20px;
}
section {
  padding: 88px 0;
}
h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.3;
}
.section-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  margin-bottom: 32px;
}
.section-head h2 {
  font-size: 28px;
  font-weight: 800;
}
.section-head .link {
  font-size: 13px;
  font-weight: 600;
  color: var(--ink-2);
  transition: color 0.2s;
}
.section-head .link:hover {
  color: var(--brand);
}

/* 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;
  padding: 0 20px;
  text-align: center;
}
.top-bar .badge {
  display: inline-block;
  font-size: 11px;
  color: #fff;
  border: 1px solid rgba(255, 255, 255, 0.5);
  border-radius: 4px;
  padding: 0 4px;
  margin-right: 6px;
  line-height: 1.4;
  vertical-align: middle;
}

/* 01 导航 */
.nav-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(252, 250, 248, 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: 8px;
  font-weight: 800;
  font-size: 18px;
}
.brand img {
  height: 32px;
  width: auto;
}
.nav-links {
  display: flex;
  gap: 24px;
  font-size: 14px;
  font-weight: 500;
  color: var(--ink-2);
}
.nav-links a {
  transition: color 0.2s;
}
.nav-links a:hover {
  color: var(--ink);
}
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: var(--brand);
  color: #fff;
  border-radius: 999px;
  padding: 8px 20px;
  font-size: 14px;
  font-weight: 600;
  transition: transform 0.2s, opacity 0.2s;
}
.btn:hover {
  transform: translateY(-1px);
  opacity: 0.9;
}
.btn-outline {
  background-color: transparent;
  color: var(--ink);
  border: 1px solid var(--line);
}
.btn-outline:hover {
  border-color: var(--brand);
}
.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  font-size: 14px;
  font-weight: 600;
  padding: 8px;
}

/* 02 首屏 */
.hero {
  padding-top: 64px;
  display: grid;
  grid-template-columns: 1.05fr 1fr;
  gap: 40px;
  align-items: center;
}
.hero-content {
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.hero-label {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--ink-3);
  font-weight: 600;
}
.hero h1 {
  font-size: clamp(36px, 5vw, 58px);
  line-height: 1.15;
  letter-spacing: -0.02em;
}
.hero-claim {
  font-size: 20px;
  font-weight: 500;
  font-style: italic;
  color: var(--brand);
}
.hero-desc {
  font-size: 15px;
  color: var(--ink-2);
  line-height: 1.85;
  max-width: 85%;
}
.hero-actions {
  display: flex;
  gap: 12px;
  margin-top: 8px;
}
.hero-tags {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: 16px;
}
.tag {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 6px 12px;
  font-size: 12px;
  color: var(--ink-2);
  background-color: var(--surface);
}
.hero-visual {
  position: relative;
  aspect-ratio: 3/4;
}
.stack {
  position: relative;
  width: 100%;
  height: 100%;
}
.stack img {
  position: absolute;
  border-radius: 12px;
  border: 1px solid #fff;
  box-shadow: 0 12px 32px rgba(0,0,0,0.12);
  object-fit: cover;
  object-position: 50% 22%;
}
.stack .main-img {
  width: 64%;
  height: auto;
  aspect-ratio: 3/4;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: 2;
}
.stack .sub-a {
  width: 32%;
  height: auto;
  aspect-ratio: 3/4;
  top: -5%;
  left: 0;
  transform: rotate(-3deg);
  z-index: 1;
}
.stack .sub-b {
  width: 32%;
  height: auto;
  aspect-ratio: 3/4;
  bottom: -5%;
  right: 0;
  transform: rotate(3deg);
  z-index: 3;
}

/* 03 双引擎对照 */
.dual-engine {
  display: grid;
  grid-template-columns: 1fr 1fr;
  position: relative;
  background-color: var(--bg-alt);
  border-radius: 20px;
  padding: 32px;
  gap: 40px;
}
.dual-engine::after {
  content: '';
  position: absolute;
  top: 32px;
  bottom: 32px;
  left: 50%;
  border-left: 1px dashed var(--line);
}
.engine-col {
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.engine-col h3 {
  font-size: 16px;
  font-weight: 600;
}
.engine-item {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.engine-tag {
  font-size: 12px;
  color: var(--brand);
  font-weight: 600;
}
.engine-desc {
  font-size: 13px;
  color: var(--ink-2);
}

/* 04 内容线入口 */
.entry-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}
.entry-card {
  background-color: var(--surface);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: transform 0.2s, border-color 0.2s;
}
.entry-card:hover {
  transform: translateY(-2px);
  border-color: var(--brand);
}
.entry-icon {
  width: 24px;
  height: 24px;
  background-color: var(--brand-soft);
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--brand);
  font-weight: bold;
  font-size: 14px;
}
.entry-card h3 {
  font-size: 18px;
  font-weight: 600;
}
.entry-card p {
  font-size: 13px;
  color: var(--ink-2);
}
.entry-link {
  margin-top: auto;
  font-size: 13px;
  font-weight: 600;
  color: var(--brand);
}

/* 05 题材频道墙 */
.channel-wall {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border: 1px solid var(--line);
  background-color: var(--surface);
}
.channel-item {
  padding: 22px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: background-color 0.2s;
  cursor: pointer;
}
.channel-item:nth-child(4n) { border-right: none; }
.channel-item:nth-last-child(-n+4) { border-bottom: none; }
.channel-item:hover {
  background-color: var(--brand-soft);
}
.channel-item h3 {
  font-size: 15px;
  font-weight: 600;
}
.channel-item span {
  font-size: 14px;
  color: var(--ink-3);
}

/* 06 排名轨道 */
.rank-track {
  display: flex;
  gap: 20px;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  padding-bottom: 16px;
}
.rank-item {
  flex: 1;
  min-width: 0;
  scroll-snap-align: start;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.rank-num {
  font-size: 40px;
  font-weight: 800;
  color: var(--brand);
  font-variant-numeric: tabular-nums;
  opacity: 0.9;
  line-height: 1;
}
.rank-cover {
  width: 100%;
  aspect-ratio: 3/4;
  border-radius: 10px;
  overflow: hidden;
  position: relative;
}
.rank-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: 50% 22%;
}
.rank-cover::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 42%, rgba(0,0,0,.5));
}
.rank-title {
  font-size: 13.5px;
  font-weight: 600;
  line-height: 1.4;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.rank-meta {
  font-size: 12px;
  color: var(--ink-2);
}

/* 07 专题片单 */
.playlists {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}
.playlist-card {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.playlist-img {
  width: 100%;
  aspect-ratio: 3/4;
  border-radius: 12px;
  overflow: hidden;
  position: relative;
}
.playlist-img img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: 50% 22%;
}
.playlist-img::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 42%, rgba(0,0,0,.5));
}
.playlist-keyword {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--brand);
  font-weight: 600;
}
.playlist-name {
  font-size: 20px;
  font-weight: 700;
}
.playlist-desc {
  font-size: 12.5px;
  color: var(--ink-2);
}

/* 08 安装区 */
.install-section {
  background-color: var(--bg-alt);
  border-radius: 24px;
  padding: 56px 32px;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
  margin: 0 20px;
}
.install-section h2 {
  font-size: 28px;
  font-weight: 700;
  line-height: 1.3;
}
.install-desc {
  font-size: 16px;
  color: var(--ink-2);
  max-width: 400px;
}
.install-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  margin-top: 8px;
}
.install-btn {
  background-color: var(--surface);
  color: var(--ink);
  border: 1px solid var(--line);
  height: 48px;
  border-radius: 999px;
  padding: 0 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 15px;
  transition: border-color 0.2s;
}
.install-btn:hover {
  border-color: var(--brand);
}
.qrcode-box {
  width: 120px;
  height: 120px;
  background-color: #fff;
  border: 1px solid var(--line);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 12px;
}
.qrcode-box div {
  width: 100%;
  height: 100%;
  background: repeating-linear-gradient(45deg, #222 0, #222 2px, #fff 2px, #fff 4px);
  border-radius: 4px;
}
.install-meta {
  font-size: 12px;
  color: var(--ink-3);
  margin-top: 16px;
}

/* 09 答疑区 */
.faq-list {
  border-top: 1px solid var(--line);
}
.faq-item {
  border-bottom: 1px solid var(--line);
}
.faq-item summary {
  display: flex;
  align-items: center;
  padding: 20px 0;
  cursor: pointer;
  list-style: none;
  user-select: none;
}
.faq-item 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 {
  width: 22px;
  height: 22px;
  position: relative;
  flex-shrink: 0;
}
.faq-icon::before,
.faq-icon::after {
  content: '';
  position: absolute;
  background-color: var(--ink-2);
  transition: transform 0.2s, opacity 0.2s;
}
.faq-icon::before {
  top: 50%; left: 0; width: 100%; height: 1px; transform: translateY(-50%);
}
.faq-icon::after {
  top: 0; left: 50%; width: 1px; height: 100%; transform: translateX(-50%);
}
details[open] .faq-icon::after {
  transform: translateX(-50%) rotate(90deg);
  opacity: 0;
}
.faq-a {
  padding: 0 0 20px 42px;
  font-size: 13.5px;
  line-height: 1.85;
  color: var(--ink-2);
}

/* 10 页脚 */
.footer {
  padding: 64px 0 88px;
  border-top: 1px solid var(--line);
  margin-top: 88px;
}
.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--line);
  margin-bottom: 24px;
}
.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.footer-brand strong {
  font-size: 20px;
  font-weight: 800;
}
.footer-brand p {
  font-size: 13px;
  color: var(--ink-2);
}
.back-to-top {
  font-size: 14px;
  font-weight: 600;
  color: var(--ink-2);
}
.back-to-top:hover {
  color: var(--ink);
}
.footer-links {
  display: flex;
  flex-direction: column;
  gap: 12px;
  font-size: 14px;
  color: var(--ink-2);
  margin-bottom: 32px;
}
.footer-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.footer-row span {
  color: var(--line);
}
.footer-bottom {
  font-size: 12px;
  color: var(--ink-3);
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.footer-age {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--ink-3);
  margin-top: 8px;
}

/* 响应式 */
@media (max-width: 900px) {
  section {
    padding: 52px 0;
  }
  .hero {
    grid-template-columns: 1fr;
    padding-top: 32px;
    gap: 32px;
  }
  .hero-desc {
    max-width: 100%;
  }
  .hero-tags {
    grid-template-columns: 1fr 1fr;
  }
  .stack .sub-a,
  .stack .sub-b {
    display: none;
  }
  .stack .main-img {
    width: 100%;
    height: 100%;
    top: 0; left: 0; transform: none;
    border-radius: 16px;
  }
  .hero-visual {
    max-width: 400px;
    margin: 0 auto;
  }
  .dual-engine {
    grid-template-columns: 1fr;
    gap: 32px;
  }
  .dual-engine::after {
    top: 50%;
    left: 32px;
    right: 32px;
    bottom: auto;
    border-left: none;
    border-top: 1px dashed var(--line);
  }
  .entry-cards {
    grid-template-columns: 1fr;
    gap: 16px;
  }
  .channel-wall {
    grid-template-columns: repeat(2, 1fr);
  }
  .channel-item:nth-child(2n) { border-right: none; }
  .channel-item:nth-child(n+5) { border-bottom: none; }
  .channel-item:nth-last-child(-n+4) { border-bottom: 1px solid var(--line); }
  .channel-item:nth-last-child(-n+2) { border-bottom: none; }
  .playlists {
    display: flex;
    overflow-x: auto;
    scroll-snap-type: x mandatory;
    gap: 16px;
    padding-bottom: 16px;
  }
  .playlist-card {
    flex: 0 0 62vw;
    scroll-snap-align: start;
  }
  .footer {
    margin-top: 52px;
    padding-bottom: 120px;
  }
  .footer-top {
    flex-direction: column;
    gap: 16px;
  }
  .install-section {
    margin: 0;
    border-radius: 16px;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  .mobile-menu-btn {
    display: block;
  }
  .nav-inner {
    height: 56px;
  }
  .nav-right {
    display: flex;
    align-items: center;
    gap: 8px;
  }
  .nav-right .btn {
    padding: 6px 14px;
    font-size: 13px;
  }
  .section-head {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }
  .rank-track {
    gap: 16px;
  }
  .rank-item {
    flex: 0 0 44vw;
  }
}

@media (max-width: 560px) {
  .hero h1 {
    font-size: 36px;
  }
  .hero-tags {
    grid-template-columns: 1fr;
  }
  .hero-tags .tag:last-child {
    grid-column: 1 / -1;
  }
  .install-actions {
    flex-direction: column;
    gap: 16px;
  }
  .install-section h2 {
    font-size: 24px;
  }
}