:root {
  --color-text: #1a1a2e;
  --color-text-secondary: #555;
  --color-text-muted: #888;
  --color-bg: #fff;
  --color-bg-alt: #f8f9fa;
  --color-bg-card: #fff;
  --color-border: #e5e7eb;
  --color-accent: #2563eb;
  --color-accent-hover: #1d4ed8;
  --color-accent-light: #eff6ff;
  --color-star: #f59e0b;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --radius: 10px;
  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
}

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

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

body {
  font-family: var(--font);
  color: var(--color-text);
  line-height: 1.6;
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

a { color: var(--color-accent); text-decoration: none; }
a:hover { color: var(--color-accent-hover); }
img { max-width: 100%; display: block; }

/* Layout */
.container { max-width: 960px; margin: 0 auto; padding: 0 20px; }
.section { padding: 60px 0; }
.section:nth-child(even) { background: var(--color-bg-alt); }
.section-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 32px;
  text-align: center;
  color: var(--color-text);
}

/* Header */
.header {
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg);
  position: sticky;
  top: 0;
  z-index: 100;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}
.site-name {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--color-text);
}
.site-name:hover { color: var(--color-accent); }
.site-logo { border-radius: 6px; }
.nav { display: flex; gap: 24px; }
.nav a {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  padding: 4px 0;
  border-bottom: 2px solid transparent;
  transition: all 0.2s;
}
.nav a:hover {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

/* Hero */
.hero {
  padding: 64px 0 48px;
  text-align: center;
  background: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border);
}
.hero h1 {
  font-size: 2rem;
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}
.hero-desc {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  max-width: 640px;
  margin: 0 auto 32px;
  line-height: 1.7;
}
.hero-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
  margin-bottom: 12px;
}
.jump-hint {
  display: block;
  font-size: 0.8rem;
  color: var(--color-text-muted);
  margin-top: 4px;
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 11px 24px;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all 0.2s;
  white-space: nowrap;
}
.btn-primary { background: var(--color-accent); color: #fff; }
.btn-primary:hover { background: var(--color-accent-hover); color: #fff; }
.btn-secondary {
  background: var(--color-bg-card);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}
.btn-secondary:hover {
  background: var(--color-accent-light);
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* Reviews */
.reviews { background: var(--color-bg); }
.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.review-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
}
.review-stars {
  color: var(--color-star);
  font-size: 1rem;
  margin-bottom: 12px;
  letter-spacing: 2px;
}
.review-text {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.65;
  margin-bottom: 16px;
}
.review-user { display: flex; align-items: center; gap: 10px; }
.review-avatar { border-radius: 50%; width: 40px; height: 40px; }
.review-name { font-size: 0.85rem; font-weight: 600; color: var(--color-text); }
.review-meta { font-size: 0.75rem; color: var(--color-text-muted); }

/* Knowledge Cards */
.cards { background: var(--color-bg-alt); }
.cards-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}
.card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
}
.card h3 { font-size: 1rem; font-weight: 700; margin-bottom: 8px; color: var(--color-text); }
.card p { font-size: 0.88rem; color: var(--color-text-secondary); line-height: 1.7; }

/* Download Hero */
.download-hero {
  padding: 56px 0 40px;
  text-align: center;
  background: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border);
}
.download-hero h1 {
  font-size: 1.6rem;
  font-weight: 800;
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}
.download-hero p { font-size: 1rem; color: var(--color-text-secondary); }

/* Platform Cards */
.platforms { padding: 48px 0 60px; background: var(--color-bg); }
.platform-grid { display: grid; grid-template-columns: 1fr; gap: 20px; }
.platform-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 28px;
}
.platform-card h2 { font-size: 1.2rem; font-weight: 700; margin-bottom: 8px; }
.platform-meta { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 16px; }
.platform-version {
  font-size: 0.8rem;
  color: var(--color-accent);
  font-weight: 600;
  background: var(--color-accent-light);
  padding: 2px 10px;
  border-radius: 4px;
}
.platform-req { font-size: 0.8rem; color: var(--color-text-muted); }
.platform-card .btn { margin-bottom: 4px; }
.platform-card .jump-hint { margin-bottom: 8px; }
.platform-variants { margin-top: 8px; font-size: 0.85rem; color: var(--color-text-muted); }
.platform-variants a { color: var(--color-accent); font-weight: 500; }
.platform-variants a:hover { text-decoration: underline; }

/* Footer */
.footer {
  padding: 40px 0;
  border-top: 1px solid var(--color-border);
  background: var(--color-bg-alt);
  text-align: center;
}
.footer p { font-size: 0.8rem; color: var(--color-text-muted); line-height: 1.8; }

/* Responsive */
@media (max-width: 768px) {
  .hero h1 { font-size: 1.5rem; }
  .hero-desc { font-size: 0.95rem; }
  .hero-buttons { flex-direction: column; align-items: center; }
  .btn { width: 100%; max-width: 300px; text-align: center; }
  .reviews-grid { grid-template-columns: 1fr; }
  .cards-grid { grid-template-columns: 1fr; }
  .download-hero h1 { font-size: 1.3rem; }
  .section-title { font-size: 1.3rem; }
}

@media (max-width: 480px) {
  .header-inner { height: 48px; }
  .site-name { font-size: 0.9rem; }
  .nav { gap: 16px; }
  .nav a { font-size: 0.8rem; }
  .hero { padding: 40px 0 32px; }
  .hero h1 { font-size: 1.3rem; }
  .section { padding: 40px 0; }
}