/* QiandaoAI Promo Site */
:root {
  --brand-1: #e84a1a;
  --brand-2: #f57c2a;
  --brand-3: #ffb347;
  --bg: #0c0a09;
  --bg-elevated: #1a1512;
  --bg-card: #211b17;
  --text: #faf7f4;
  --text-muted: #a89f96;
  --border: rgba(255, 180, 100, 0.12);
  --gradient: linear-gradient(135deg, var(--brand-1), var(--brand-2) 50%, var(--brand-3));
  --shadow: 0 24px 80px rgba(232, 74, 26, 0.18);
  --radius: 16px;
  --radius-lg: 24px;
  --header-h: 72px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

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

.container {
  width: min(1120px, calc(100% - 48px));
  margin-inline: auto;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 12px 24px;
  border-radius: 12px;
  font-weight: 600;
  font-size: 0.95rem;
  border: none;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s, background 0.2s;
  white-space: nowrap;
}

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

.btn-sm {
  padding: 8px 18px;
  font-size: 0.875rem;
}

.btn-lg {
  padding: 14px 28px;
  font-size: 1rem;
}

.btn-xl {
  padding: 18px 32px;
  font-size: 1rem;
  border-radius: 14px;
  text-align: left;
}

.btn-xl span {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.btn-xl small {
  font-weight: 400;
  opacity: 0.85;
  font-size: 0.8rem;
}

.btn-primary {
  background: var(--gradient);
  color: #fff;
  box-shadow: 0 8px 32px rgba(232, 74, 26, 0.35);
}

.btn-primary:hover {
  box-shadow: 0 12px 40px rgba(232, 74, 26, 0.45);
}

.btn-outline {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-outline:hover {
  background: rgba(255, 180, 100, 0.08);
  border-color: rgba(255, 180, 100, 0.3);
}

/* Header */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--header-h);
  background: rgba(12, 10, 9, 0.82);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}

.nav {
  display: flex;
  align-items: center;
  height: 100%;
  gap: 32px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.nav-logo {
  width: 36px;
  height: 36px;
  border-radius: 8px;
}

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

.nav-links {
  display: flex;
  list-style: none;
  gap: 32px;
  margin-left: auto;
}

.nav-links a {
  color: var(--text-muted);
  font-size: 0.925rem;
  transition: color 0.2s;
}

.nav-links a:hover {
  color: var(--text);
}

.nav-cta {
  flex-shrink: 0;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  margin-left: auto;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.2s, opacity 0.2s;
}

/* Hero */
.hero {
  position: relative;
  padding: calc(var(--header-h) + 64px) 0 80px;
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 20% 40%, rgba(232, 74, 26, 0.22), transparent),
    radial-gradient(ellipse 60% 50% at 80% 20%, rgba(245, 124, 42, 0.15), transparent),
    radial-gradient(ellipse 50% 40% at 60% 80%, rgba(255, 179, 71, 0.08), transparent);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}

.hero-badge {
  display: inline-block;
  padding: 6px 14px;
  border-radius: 999px;
  background: rgba(232, 74, 26, 0.15);
  border: 1px solid rgba(232, 74, 26, 0.3);
  color: var(--brand-3);
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: 20px;
}

.hero h1 {
  font-size: clamp(2.2rem, 5vw, 3.4rem);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
}

.gradient-text {
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-desc {
  color: var(--text-muted);
  font-size: 1.05rem;
  max-width: 520px;
  margin-bottom: 32px;
}

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

.hero-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.hero-tags span {
  padding: 5px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border);
  font-size: 0.8rem;
  color: var(--text-muted);
}

.hero-card {
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  background: var(--bg-card);
}

.hero-screenshot {
  width: 100%;
  height: auto;
}

/* Stats */
.stats {
  padding: 0 0 64px;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
}

.stat-item {
  background: var(--bg-elevated);
  padding: 28px 20px;
  text-align: center;
}

.stat-item strong {
  display: block;
  font-size: 2rem;
  font-weight: 800;
  background: var(--gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 4px;
}

.stat-item span {
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* Sections */
.section {
  padding: 80px 0;
}

.section-alt {
  background: var(--bg-elevated);
  border-block: 1px solid var(--border);
}

.section-header {
  text-align: center;
  margin-bottom: 56px;
}

.section-header h2 {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 800;
  margin-bottom: 12px;
}

.section-header p {
  color: var(--text-muted);
  font-size: 1.05rem;
  max-width: 560px;
  margin-inline: auto;
}

/* Features */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  transition: border-color 0.2s, transform 0.2s;
}

.feature-card:hover {
  border-color: rgba(232, 74, 26, 0.35);
  transform: translateY(-4px);
}

.feature-icon {
  font-size: 1.8rem;
  margin-bottom: 16px;
}

.feature-card h3 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 0.9rem;
  line-height: 1.7;
}

/* Compare table */
.compare-table-wrap {
  overflow-x: auto;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}

.compare-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.925rem;
}

.compare-table th,
.compare-table td {
  padding: 16px 24px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.compare-table thead th {
  background: var(--bg-card);
  font-weight: 600;
  color: var(--text-muted);
}

.compare-table tbody tr:last-child td {
  border-bottom: none;
}

.compare-table tbody tr:hover td {
  background: rgba(255, 180, 100, 0.03);
}

.compare-table td:not(:first-child) {
  color: var(--text-muted);
}

.highlight-col {
  background: rgba(232, 74, 26, 0.08) !important;
  color: var(--text) !important;
}

.compare-table th.highlight-col {
  color: var(--brand-3);
}

/* Download */
.download-section {
  padding-bottom: 100px;
}

.download-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 48px;
  box-shadow: var(--shadow);
}

.download-info h2 {
  font-size: 1.8rem;
  font-weight: 800;
  margin-bottom: 14px;
}

.download-info p {
  color: var(--text-muted);
  margin-bottom: 20px;
}

.download-notes {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.download-notes li {
  color: var(--text-muted);
  font-size: 0.9rem;
  padding-left: 20px;
  position: relative;
}

.download-notes li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: var(--brand-3);
  font-weight: 700;
}

.download-actions {
  display: flex;
  flex-direction: column;
  gap: 16px;
  align-items: flex-start;
}

.platform-soon {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.platform-badge {
  padding: 6px 14px;
  border-radius: 999px;
  font-size: 0.8rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border);
  color: var(--text-muted);
}

.platform-badge.disabled {
  opacity: 0.6;
}

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

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 14px;
}

.footer-logo {
  width: 40px;
  height: 40px;
  border-radius: 10px;
}

.footer-brand strong {
  display: block;
  font-size: 1rem;
}

.footer-brand p {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-meta p {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* Responsive */
@media (max-width: 900px) {
  .hero-inner,
  .features-grid,
  .download-card {
    grid-template-columns: 1fr;
  }

  .hero-visual {
    order: -1;
  }

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

  .nav-toggle {
    display: flex;
  }

  .nav-cta {
    display: none;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: var(--header-h);
    left: 0;
    right: 0;
    flex-direction: column;
    gap: 0;
    background: rgba(12, 10, 9, 0.97);
    border-bottom: 1px solid var(--border);
    padding: 12px 24px 20px;
    margin-left: 0;
  }

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

  .nav-links li a {
    display: block;
    padding: 12px 0;
    border-bottom: 1px solid var(--border);
  }

  .download-card {
    padding: 32px 24px;
  }

  .download-actions {
    align-items: stretch;
  }

  .btn-xl {
    justify-content: center;
    text-align: center;
  }

  .btn-xl span {
    align-items: center;
  }
}

@media (max-width: 600px) {
  .container {
    width: calc(100% - 32px);
  }

  .features-grid {
    grid-template-columns: 1fr;
  }

  .hero-actions {
    flex-direction: column;
  }

  .hero-actions .btn {
    width: 100%;
  }
}