/* 抖阴官方站 - Mobile First */
:root {
  --bg-deep: #07070f;
  --bg-base: #0d0d1a;
  --bg-elevated: #141428;
  --bg-card: #1a1a32;
  --bg-soft: #22223a;
  --line: rgba(255, 255, 255, 0.08);
  --line-strong: rgba(255, 255, 255, 0.14);
  --text: #f2f2f7;
  --text-secondary: #b8b8c8;
  --text-muted: #8a8a9c;
  --cyan: #25f4ee;
  --magenta: #fe2c55;
  --pink: #ff4d7a;
  --accent: #ff3b6b;
  --accent-soft: rgba(254, 44, 85, 0.16);
  --cyan-soft: rgba(37, 244, 238, 0.14);
  --gradient-brand: linear-gradient(135deg, #25f4ee 0%, #fe2c55 100%);
  --gradient-hero: radial-gradient(ellipse at 20% 20%, rgba(37, 244, 238, 0.18), transparent 45%),
    radial-gradient(ellipse at 80% 10%, rgba(254, 44, 85, 0.22), transparent 40%),
    radial-gradient(ellipse at 60% 80%, rgba(120, 60, 255, 0.12), transparent 50%),
    linear-gradient(180deg, #0a0a16 0%, #07070f 100%);
  --shadow-glow: 0 0 40px rgba(254, 44, 85, 0.25);
  --shadow-phone: 0 28px 60px rgba(0, 0, 0, 0.55), 0 0 0 1px rgba(255, 255, 255, 0.06);
  --radius: 16px;
  --radius-sm: 10px;
  --nav-h: 64px;
  --promo-h: auto;
  --container: 1120px;
  --font: "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--font);
  background: var(--bg-deep);
  color: var(--text);
  line-height: 1.75;
  font-size: 15px;
  overflow-x: hidden;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--cyan);
  text-decoration: none;
  transition: color 0.2s ease, opacity 0.2s ease;
}

a:hover {
  color: var(--pink);
}

ul, ol {
  padding-left: 1.2em;
}

h1, h2, h3, h4 {
  line-height: 1.35;
  font-weight: 700;
  margin: 0 0 0.75em;
  letter-spacing: 0.01em;
}

h1 { font-size: clamp(1.75rem, 5vw, 2.75rem); }
h2 { font-size: clamp(1.4rem, 3.5vw, 2rem); }
h3 { font-size: clamp(1.1rem, 2.5vw, 1.35rem); color: #fff; }

p { margin: 0 0 1em; color: var(--text-secondary); }

.container {
  width: min(100% - 2rem, var(--container));
  margin-inline: auto;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  background: var(--magenta);
  color: #fff;
  padding: 0.5rem 1rem;
  z-index: 9999;
}

.skip-link:focus { left: 1rem; top: 1rem; }

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(7, 7, 15, 0.92);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--line);
}

.nav-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--nav-h);
  gap: 1rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  color: #fff;
  flex-shrink: 0;
}

.brand img {
  height: 36px;
  width: auto;
}

.brand-name {
  font-size: 1.15rem;
  font-weight: 700;
  background: var(--gradient-brand);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.nav-toggle {
  display: flex;
  flex-direction: column;
  gap: 5px;
  background: transparent;
  border: 0;
  padding: 8px;
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: #fff;
  border-radius: 2px;
  transition: 0.25s;
}

.nav-menu {
  display: none;
  position: absolute;
  left: 0;
  right: 0;
  top: var(--nav-h);
  background: rgba(13, 13, 26, 0.98);
  border-bottom: 1px solid var(--line);
  padding: 0.75rem 1rem 1rem;
  flex-direction: column;
  gap: 0.25rem;
}

.nav-menu.open { display: flex; }

.nav-menu a {
  color: var(--text-secondary);
  padding: 0.7rem 0.85rem;
  border-radius: 8px;
  font-size: 0.95rem;
}

.nav-menu a:hover,
.nav-menu a.active {
  color: #fff;
  background: var(--accent-soft);
}

.nav-cta {
  display: none;
}

/* Sticky promo bar */
.promo-bar {
  position: sticky;
  top: var(--nav-h);
  z-index: 999;
  background: linear-gradient(90deg, rgba(20, 20, 40, 0.98), rgba(30, 12, 28, 0.98));
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(12px);
}

.promo-inner {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.55rem;
  min-height: var(--promo-h);
  padding: 0.55rem 0;
}

.promo-item {
  display: flex;
  align-items: center;
  gap: 0.45rem;
  min-width: 0;
  padding: 0.4rem 0.55rem 0.4rem 0.35rem;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--line);
  color: #fff;
}

.promo-item:hover {
  border-color: rgba(254, 44, 85, 0.45);
  color: #fff;
}

.promo-item.primary {
  background: linear-gradient(135deg, rgba(37, 244, 238, 0.12), rgba(254, 44, 85, 0.22));
  border-color: rgba(254, 44, 85, 0.4);
  box-shadow: 0 0 20px rgba(254, 44, 85, 0.15);
}

.promo-item img {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  object-fit: cover;
}

.promo-meta {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
  min-width: 0;
}

.promo-meta strong {
  font-size: 0.78rem;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.promo-meta span {
  font-size: 0.66rem;
  color: var(--text-muted);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.promo-item.primary .promo-meta span {
  color: #ffb3c4;
}

/* Hero */
.hero {
  position: relative;
  padding: 2.5rem 0 3rem;
  background: var(--gradient-hero);
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(90deg, transparent 0%, rgba(37, 244, 238, 0.03) 50%, transparent 100%);
  pointer-events: none;
}

.hero-grid {
  position: relative;
  display: grid;
  gap: 2.5rem;
  align-items: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  background: var(--cyan-soft);
  border: 1px solid rgba(37, 244, 238, 0.3);
  color: var(--cyan);
  font-size: 0.78rem;
  margin-bottom: 1rem;
}

.hero h1 {
  margin-bottom: 0.75rem;
  background: linear-gradient(180deg, #fff 30%, #c9c9d8);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-lead {
  font-size: 1.05rem;
  color: #d4d4e0;
  margin-bottom: 1rem;
}

.hero-desc {
  max-width: 36rem;
}

.hero-points {
  list-style: none;
  padding: 0;
  margin: 1.25rem 0 1.75rem;
  display: grid;
  gap: 0.65rem;
}

.hero-points li {
  display: flex;
  align-items: flex-start;
  gap: 0.65rem;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.hero-points li::before {
  content: "";
  width: 8px;
  height: 8px;
  margin-top: 0.5rem;
  border-radius: 50%;
  background: var(--gradient-brand);
  flex-shrink: 0;
  box-shadow: 0 0 10px rgba(37, 244, 238, 0.6);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.45rem;
  padding: 0.85rem 1.35rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
}

.btn:hover { transform: translateY(-1px); }

.btn-primary {
  background: var(--gradient-brand);
  color: #0a0a12;
  box-shadow: var(--shadow-glow);
}

.btn-primary:hover { color: #0a0a12; }

.btn-ghost {
  background: rgba(255, 255, 255, 0.04);
  border-color: var(--line-strong);
  color: #fff;
}

.btn-ghost:hover { color: #fff; border-color: rgba(37, 244, 238, 0.4); }

.hero-visual {
  position: relative;
  min-height: 340px;
  display: flex;
  justify-content: center;
  align-items: center;
  perspective: 1200px;
}

.phone {
  width: min(52%, 220px);
  border-radius: 22px;
  overflow: hidden;
  box-shadow: var(--shadow-phone);
  border: 1px solid rgba(255, 255, 255, 0.1);
  background: #000;
  position: absolute;
}

.phone img {
  width: 100%;
  height: auto;
  display: block;
}

.phone-main {
  z-index: 2;
  transform: translate(18%, 0) rotate(-2deg);
  filter: drop-shadow(0 20px 40px rgba(0, 0, 0, 0.6));
}

.phone-back {
  z-index: 1;
  transform: translate(-22%, 8%) rotate(6deg) scale(0.92);
  opacity: 0.88;
  filter: blur(0.2px) brightness(0.85);
}

.hero-glow {
  position: absolute;
  width: 260px;
  height: 260px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(254, 44, 85, 0.35), transparent 70%);
  filter: blur(20px);
  z-index: 0;
  animation: pulseGlow 5s ease-in-out infinite;
}

@keyframes pulseGlow {
  0%, 100% { transform: scale(1); opacity: 0.7; }
  50% { transform: scale(1.15); opacity: 1; }
}

/* Sections */
.section {
  padding: 3.5rem 0;
  position: relative;
}

.section-alt {
  background: linear-gradient(180deg, rgba(20, 20, 40, 0.45), transparent);
}

.section-head {
  margin-bottom: 1.75rem;
  max-width: 46rem;
}

.section-head .eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 0.55rem;
}

.section-head p {
  margin-bottom: 0;
}

/* Cards / grids */
.feature-grid {
  display: grid;
  gap: 1rem;
}

.feature-card {
  background: linear-gradient(160deg, rgba(26, 26, 50, 0.9), rgba(16, 16, 32, 0.95));
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 1.35rem 1.25rem;
  transition: border-color 0.25s ease, transform 0.25s ease;
}

.feature-card:hover {
  border-color: rgba(37, 244, 238, 0.35);
  transform: translateY(-2px);
}

.feature-card .icon-dot {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  background: var(--gradient-brand);
  color: #0a0a12;
  font-weight: 800;
  margin-bottom: 0.9rem;
}

.feature-card p { margin-bottom: 0; font-size: 0.92rem; }

/* Video grid */
.video-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.85rem;
}

.video-card {
  border-radius: 12px;
  overflow: hidden;
  background: var(--bg-card);
  border: 1px solid var(--line);
  transition: transform 0.2s ease, border-color 0.2s ease;
}

.video-card:hover {
  transform: translateY(-3px);
  border-color: rgba(254, 44, 85, 0.4);
}

.video-card .thumb {
  aspect-ratio: 3 / 4;
  overflow: hidden;
  background: #111;
}

.video-card .thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.video-card .info {
  padding: 0.7rem 0.75rem 0.9rem;
}

.video-card .info h3 {
  font-size: 0.82rem;
  margin: 0 0 0.35rem;
  font-weight: 600;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.video-card .info span {
  font-size: 0.72rem;
  color: var(--text-muted);
}

/* Content layout with images */
.content-block {
  display: grid;
  gap: 1.5rem;
  margin-bottom: 2.5rem;
  align-items: center;
}

.content-block .shot {
  border-radius: 18px;
  overflow: hidden;
  border: 1px solid var(--line);
  box-shadow: var(--shadow-phone);
  max-width: 280px;
  margin-inline: auto;
}

.content-block .shot img {
  width: 100%;
}

.prose h2 { margin-top: 0; }
.prose h3 { margin-top: 1.5rem; }

.prose .inline-link {
  color: var(--pink);
  border-bottom: 1px solid rgba(254, 44, 85, 0.35);
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 1rem 0;
  padding: 0;
  list-style: none;
}

.tag-list li {
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--line);
  color: var(--text-secondary);
  font-size: 0.8rem;
}

/* CTA band */
.cta-band {
  margin: 1rem 0;
  padding: 2rem 1.25rem;
  border-radius: var(--radius);
  background:
    radial-gradient(circle at 15% 30%, rgba(37, 244, 238, 0.2), transparent 40%),
    radial-gradient(circle at 85% 70%, rgba(254, 44, 85, 0.25), transparent 45%),
    linear-gradient(135deg, #16162c, #1c1020);
  border: 1px solid var(--line-strong);
  text-align: center;
}

.cta-band h2 { margin-bottom: 0.5rem; }
.cta-band p { max-width: 36rem; margin: 0 auto 1.25rem; }
.cta-apps {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75rem;
}

.app-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.55rem 1rem 0.55rem 0.55rem;
  border-radius: 999px;
  background: rgba(0, 0, 0, 0.35);
  border: 1px solid var(--line);
  color: #fff;
}

.app-chip img {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  object-fit: cover;
}

.app-chip.primary {
  background: linear-gradient(135deg, rgba(37, 244, 238, 0.18), rgba(254, 44, 85, 0.28));
  border-color: rgba(254, 44, 85, 0.5);
}

/* FAQ */
.faq-list {
  display: grid;
  gap: 0.75rem;
}

.faq-item {
  background: var(--bg-elevated);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.faq-item summary {
  padding: 1rem 1.15rem;
  cursor: pointer;
  font-weight: 600;
  list-style: none;
  color: #fff;
}

.faq-item summary::-webkit-details-marker { display: none; }

.faq-item summary::after {
  content: "+";
  float: right;
  color: var(--cyan);
  font-weight: 400;
}

.faq-item[open] summary::after { content: "–"; }

.faq-item .faq-body {
  padding: 0 1.15rem 1.15rem;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* Breadcrumb */
.breadcrumb {
  padding: 1rem 0 0;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.breadcrumb a { color: var(--text-secondary); }
.breadcrumb span { color: var(--text-muted); }

.page-hero {
  padding: 1.5rem 0 2rem;
  background: var(--gradient-hero);
  border-bottom: 1px solid var(--line);
}

.page-hero h1 { margin-bottom: 0.5rem; }

.legal-content,
.article-content {
  padding: 2.5rem 0 3.5rem;
  max-width: 820px;
}

.legal-content h2,
.article-content h2 {
  margin-top: 2rem;
  padding-top: 0.5rem;
}

.download-grid {
  display: grid;
  gap: 1rem;
  margin: 1.5rem 0;
}

.download-card {
  display: grid;
  grid-template-columns: 72px 1fr;
  gap: 1rem;
  align-items: center;
  padding: 1.15rem;
  border-radius: var(--radius);
  background: var(--bg-elevated);
  border: 1px solid var(--line);
}

.download-card.featured {
  border-color: rgba(254, 44, 85, 0.45);
  background: linear-gradient(135deg, rgba(37, 244, 238, 0.08), rgba(254, 44, 85, 0.12));
}

.download-card img {
  width: 72px;
  height: 72px;
  border-radius: 16px;
  object-fit: cover;
}

.download-card h3 { margin: 0 0 0.25rem; font-size: 1.05rem; }
.download-card p { margin: 0 0 0.75rem; font-size: 0.85rem; }

.related {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
}

.related ul {
  list-style: none;
  padding: 0;
  display: grid;
  gap: 0.5rem;
}

.related a {
  display: block;
  padding: 0.75rem 1rem;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--line);
  color: var(--text-secondary);
}

.related a:hover {
  color: #fff;
  border-color: rgba(37, 244, 238, 0.35);
}

/* Error pages */
.error-page {
  min-height: 70vh;
  display: grid;
  place-items: center;
  text-align: center;
  padding: 3rem 1rem;
  background: var(--gradient-hero);
}

.error-page .code {
  font-size: clamp(4rem, 15vw, 7rem);
  font-weight: 800;
  background: var(--gradient-brand);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  line-height: 1;
  margin-bottom: 0.5rem;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--line);
  background: #05050c;
  padding: 2.5rem 0 2rem;
  margin-top: 1rem;
}

.footer-grid {
  display: grid;
  gap: 1.75rem;
}

.footer-brand p {
  font-size: 0.9rem;
  max-width: 28rem;
}

.footer-links h4 {
  margin: 0 0 0.75rem;
  font-size: 0.9rem;
  color: #fff;
}

.footer-links ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.45rem;
}

.footer-links a {
  color: var(--text-muted);
  font-size: 0.88rem;
}

.footer-links a:hover { color: var(--cyan); }

.footer-bottom {
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line);
  font-size: 0.8rem;
  color: var(--text-muted);
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  justify-content: space-between;
}

.age-note {
  display: inline-block;
  margin-top: 0.75rem;
  padding: 0.35rem 0.7rem;
  border: 1px solid rgba(254, 44, 85, 0.4);
  border-radius: 6px;
  color: var(--pink);
  font-size: 0.78rem;
}

/* Animations */
@media (prefers-reduced-motion: no-preference) {
  .reveal {
    opacity: 0;
    transform: translateY(18px);
    transition: opacity 0.6s ease, transform 0.6s ease;
  }
  .reveal.visible {
    opacity: 1;
    transform: none;
  }
  .phone-main {
    animation: floatMain 6s ease-in-out infinite;
  }
  .phone-back {
    animation: floatBack 7s ease-in-out infinite;
  }
}

@keyframes floatMain {
  0%, 100% { transform: translate(18%, 0) rotate(-2deg); }
  50% { transform: translate(18%, -10px) rotate(-1deg); }
}

@keyframes floatBack {
  0%, 100% { transform: translate(-22%, 8%) rotate(6deg) scale(0.92); }
  50% { transform: translate(-22%, 14px) rotate(5deg) scale(0.92); }
}

/* Desktop */
@media (min-width: 768px) {
  body { font-size: 16px; }

  .nav-toggle { display: none; }

  .nav-menu {
    display: flex;
    position: static;
    flex-direction: row;
    align-items: center;
    background: transparent;
    border: 0;
    padding: 0;
    gap: 0.15rem;
  }

  .nav-menu a {
    padding: 0.45rem 0.7rem;
    font-size: 0.9rem;
  }

  .nav-cta {
    display: inline-flex;
    margin-left: 0.5rem;
    padding: 0.55rem 1rem;
    font-size: 0.85rem;
  }

  .hero {
    padding: 4rem 0 4.5rem;
  }

  .hero-grid {
    grid-template-columns: 1.05fr 0.95fr;
    gap: 2rem;
  }

  .hero-visual {
    min-height: 480px;
  }

  .phone {
    width: min(48%, 250px);
  }

  .feature-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .video-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 1.1rem;
  }

  .content-block {
    grid-template-columns: 1fr 240px;
    gap: 2.5rem;
  }

  .content-block.reverse {
    grid-template-columns: 240px 1fr;
  }

  .content-block.reverse .prose { order: 2; }
  .content-block.reverse .shot { order: 1; }

  .download-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .footer-grid {
    grid-template-columns: 1.4fr 1fr 1fr 1fr;
  }

  .section { padding: 4.5rem 0; }

  .promo-inner {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 0.75rem;
  }

  .promo-item {
    border-radius: 999px;
    padding: 0.45rem 0.95rem 0.45rem 0.45rem;
  }

  .promo-meta strong { font-size: 0.82rem; }
  .promo-meta span { font-size: 0.68rem; }
}

@media (min-width: 1024px) {
  .feature-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .video-grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .promo-item img {
    width: 40px;
    height: 40px;
  }
}