/* Douyin 抖阴官网 - dyapp.lat */
:root {
  --bg-primary: #0d0d0f;
  --bg-secondary: #1a1625;
  --bg-card: #1e1a28;
  --accent: #ff2d55;
  --accent-cyan: #25f4ee;
  --accent-magenta: #fe2c55;
  --text-primary: #ffffff;
  --text-secondary: #a0a0b0;
  --text-muted: #6b6b7b;
  --border: #2a2535;
  --radius: 12px;
  --shadow: 0 4px 24px rgba(0,0,0,.4);
  --max-width: 1200px;
  --header-height: 64px;
  --dy-ads-height: 0px;
}

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

html { scroll-behavior: smooth; font-size: 16px; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
}

a { color: var(--accent-cyan); text-decoration: none; transition: color .2s; }
a:hover { color: var(--accent); }

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

.container { max-width: var(--max-width); margin: 0 auto; padding: 0 20px; }

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 300;
  background: rgba(13,13,15,.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  height: var(--header-height);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
}

.logo-link {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--text-primary);
}

.logo-link:hover { color: var(--text-primary); }

.logo-link img { width: 40px; height: 40px; border-radius: 8px; }

.logo-text {
  font-size: 1.25rem;
  font-weight: 700;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-magenta));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-desktop { display: flex; gap: 28px; list-style: none; }
.nav-desktop a { color: var(--text-secondary); font-size: .95rem; }
.nav-desktop a:hover, .nav-desktop a.active { color: var(--text-primary); }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: 1.5rem;
  cursor: pointer;
  padding: 4px;
}

.nav-mobile {
  display: none;
  position: fixed;
  top: calc(var(--header-height) + var(--dy-ads-height));
  left: 0; right: 0;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  padding: 16px 20px;
  z-index: 250;
  max-height: calc(100vh - var(--header-height) - var(--dy-ads-height));
  overflow-y: auto;
}

.nav-mobile.open { display: block; }
.nav-mobile ul { list-style: none; }
.nav-mobile li { border-bottom: 1px solid var(--border); }
.nav-mobile a {
  display: block;
  padding: 14px 0;
  color: var(--text-secondary);
}

/* Hero */
.hero {
  padding: 60px 0 50px;
  background: linear-gradient(180deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
  text-align: center;
}

.hero h1 {
  font-size: clamp(1.75rem, 4vw, 2.75rem);
  line-height: 1.3;
  margin-bottom: 20px;
}

.hero-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 720px;
  margin: 0 auto 32px;
}

.btn-group { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: 50px;
  font-size: 1rem;
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: transform .2s, box-shadow .2s;
}

.btn:hover { transform: translateY(-2px); }

.btn-primary {
  background: linear-gradient(135deg, var(--accent), #e02050);
  color: #fff;
  box-shadow: 0 4px 20px rgba(255,45,85,.35);
}

.btn-primary:hover { color: #fff; box-shadow: 0 6px 28px rgba(255,45,85,.5); }

.btn-outline {
  background: transparent;
  color: var(--text-primary);
  border: 2px solid var(--border);
}

.btn-outline:hover { border-color: var(--accent-cyan); color: var(--accent-cyan); }

/* Sections */
section { padding: 50px 0; }

.section-title {
  font-size: 1.75rem;
  margin-bottom: 12px;
  text-align: center;
}

.section-desc {
  text-align: center;
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto 40px;
}

/* Feature grid */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  transition: border-color .2s, transform .2s;
}

.feature-card:hover {
  border-color: var(--accent);
  transform: translateY(-4px);
}

.feature-card h3 { font-size: 1.15rem; margin-bottom: 10px; }
.feature-card p { color: var(--text-secondary); font-size: .95rem; }

.feature-icon {
  width: 48px; height: 48px;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent));
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  margin-bottom: 16px;
}

/* Screenshot gallery */
.gallery-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
}

.gallery-item {
  background: var(--bg-card);
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  transition: transform .2s;
}

.gallery-item:hover { transform: scale(1.02); }

.gallery-item img { width: 100%; aspect-ratio: 9/16; object-fit: cover; object-position: top; }

.gallery-caption {
  padding: 14px 16px;
  font-size: .9rem;
  color: var(--text-secondary);
}

.gallery-caption strong { color: var(--text-primary); display: block; margin-bottom: 4px; }

/* Content article */
.content-article {
  max-width: 900px;
  margin: 0 auto;
}

.content-article h2 {
  font-size: 1.5rem;
  margin: 36px 0 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--accent);
}

.content-article h3 {
  font-size: 1.2rem;
  margin: 28px 0 12px;
  color: var(--accent-cyan);
}

.content-article p {
  margin-bottom: 16px;
  color: var(--text-secondary);
}

.content-article ul, .content-article ol {
  margin: 12px 0 16px 24px;
  color: var(--text-secondary);
}

.content-article li { margin-bottom: 8px; }

.content-article .highlight-box {
  background: var(--bg-card);
  border-left: 4px solid var(--accent);
  padding: 20px 24px;
  border-radius: 0 var(--radius) var(--radius) 0;
  margin: 24px 0;
}

.content-article .highlight-box p { margin-bottom: 0; }

/* Category tags */
.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 20px 0;
}

.tag {
  display: inline-block;
  padding: 6px 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 20px;
  font-size: .85rem;
  color: var(--text-secondary);
}

/* FAQ */
.faq-list { max-width: 800px; margin: 0 auto; }

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 12px;
  overflow: hidden;
}

.faq-question {
  padding: 18px 24px;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-answer {
  padding: 0 24px 18px;
  color: var(--text-secondary);
  font-size: .95rem;
}

/* Page header for subpages */
.page-header {
  padding: 48px 0 32px;
  background: var(--bg-secondary);
  text-align: center;
  border-bottom: 1px solid var(--border);
}

.page-header h1 { font-size: 2rem; margin-bottom: 8px; }
.page-header p { color: var(--text-secondary); }

/* Legal pages */
.legal-content {
  max-width: 860px;
  margin: 0 auto;
  padding: 40px 20px 60px;
}

.legal-content h2 {
  font-size: 1.3rem;
  margin: 32px 0 12px;
  color: var(--accent-cyan);
}

.legal-content p, .legal-content li {
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.legal-content ul { margin-left: 24px; }

/* Error pages */
.error-page {
  min-height: calc(100vh - 200px);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 60px 20px;
}

.error-code {
  font-size: 6rem;
  font-weight: 800;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
}

.error-page h1 { font-size: 1.5rem; margin: 16px 0 8px; }
.error-page p { color: var(--text-secondary); margin-bottom: 24px; }

/* Footer */
.site-footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border);
  padding: 48px 0 24px;
  margin-top: 40px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 32px;
}

.footer-brand p {
  color: var(--text-secondary);
  font-size: .9rem;
  margin-top: 12px;
  max-width: 320px;
}

.footer-links h4 {
  font-size: .95rem;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.footer-links ul { list-style: none; }
.footer-links li { margin-bottom: 10px; }
.footer-links a { color: var(--text-secondary); font-size: .9rem; }
.footer-links a:hover { color: var(--accent-cyan); }

.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 20px;
  text-align: center;
  color: var(--text-muted);
  font-size: .85rem;
}

/* Breadcrumb */
.breadcrumb {
  padding: 16px 0;
  font-size: .85rem;
  color: var(--text-muted);
}

.breadcrumb a { color: var(--text-secondary); }
.breadcrumb span { margin: 0 8px; }

/* Download steps */
.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  margin: 32px 0;
}

.step-card {
  text-align: center;
  padding: 28px 20px;
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.step-num {
  width: 40px; height: 40px;
  background: var(--accent);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  margin: 0 auto 14px;
}

/* Responsive */
@media (max-width: 768px) {
  .nav-desktop { display: none; }
  .nav-toggle { display: block; }

  .hero { padding: 40px 0 36px; }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 28px;
  }

  .gallery-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }

  .gallery-item img { aspect-ratio: 9/14; }

  .content-article h2 { font-size: 1.3rem; }
}

@media (max-width: 480px) {
  .gallery-grid { grid-template-columns: 1fr 1fr; }
  .btn { padding: 12px 24px; font-size: .9rem; }
}