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

body {
  font-family: -apple-system, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  line-height: 1.6;
  color: #333;
  background: #fff;
  -webkit-font-smoothing: antialiased;
}

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

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

.container {
  max-width: 1000px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ── Header ── */

.header {
  background: #fff;
  border-bottom: 1px solid #e5e7eb;
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 16px;
  font-weight: 600;
  color: #111;
}

.logo img {
  width: 28px;
  height: 28px;
  border-radius: 6px;
}

.nav {
  display: flex;
  gap: 28px;
}

.nav-link {
  font-size: 14px;
  color: #666;
  padding: 16px 0;
  border-bottom: 2px solid transparent;
  transition: color 0.2s;
}

.nav-link:hover {
  color: #111;
}

.nav-link.active {
  color: #111;
  border-bottom-color: #2563eb;
}

/* ── Hero (index) ── */

.hero {
  padding: 72px 0 56px;
  text-align: center;
  background: linear-gradient(180deg, #f8fafc 0%, #fff 100%);
}

.hero h1 {
  font-size: 34px;
  font-weight: 700;
  color: #111;
  line-height: 1.35;
  margin-bottom: 20px;
}

.hero-desc {
  font-size: 16px;
  color: #555;
  line-height: 1.8;
  max-width: 680px;
  margin: 0 auto 36px;
}

.hero-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 10px;
}

.hero-note {
  font-size: 13px;
  color: #999;
}

/* ── Buttons ── */

.btn-primary {
  display: inline-block;
  padding: 12px 28px;
  background: #2563eb;
  color: #fff;
  border-radius: 6px;
  font-size: 15px;
  font-weight: 500;
  transition: background 0.2s, box-shadow 0.2s;
}

.btn-primary:hover {
  background: #1d4ed8;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.25);
}

.btn-outline {
  display: inline-block;
  padding: 12px 28px;
  background: #fff;
  color: #333;
  border: 1px solid #d1d5db;
  border-radius: 6px;
  font-size: 15px;
  font-weight: 500;
  transition: border-color 0.2s, color 0.2s;
}

.btn-outline:hover {
  border-color: #2563eb;
  color: #2563eb;
}

/* ── Section Title ── */

.section-title {
  font-size: 22px;
  font-weight: 700;
  color: #111;
  text-align: center;
  margin-bottom: 36px;
}

/* ── Reviews ── */

.reviews {
  padding: 56px 0;
  background: #fff;
}

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

.review-card {
  background: #f9fafb;
  border: 1px solid #e5e7eb;
  border-radius: 10px;
  padding: 24px;
}

.review-stars {
  color: #f59e0b;
  font-size: 15px;
  margin-bottom: 10px;
  letter-spacing: 2px;
}

.review-text {
  font-size: 14px;
  color: #555;
  line-height: 1.75;
  margin-bottom: 18px;
}

.review-user {
  display: flex;
  align-items: center;
  gap: 10px;
}

.review-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  flex-shrink: 0;
}

.review-name {
  font-size: 14px;
  font-weight: 600;
  color: #111;
}

.review-meta {
  font-size: 12px;
  color: #999;
}

/* ── Knowledge Cards ── */

.knowledge {
  padding: 56px 0 64px;
  background: #f8fafc;
}

.knowledge-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.knowledge-card {
  background: #fff;
  border: 1px solid #e5e7eb;
  border-radius: 10px;
  padding: 24px;
}

.knowledge-card h3 {
  font-size: 15px;
  font-weight: 600;
  color: #111;
  margin-bottom: 8px;
}

.knowledge-card p {
  font-size: 14px;
  color: #555;
  line-height: 1.75;
}

/* ── Download Hero ── */

.dl-hero {
  padding: 56px 0 36px;
  text-align: center;
  background: linear-gradient(180deg, #f8fafc 0%, #fff 100%);
}

.dl-hero h1 {
  font-size: 28px;
  font-weight: 700;
  color: #111;
  line-height: 1.35;
  margin-bottom: 10px;
}

.dl-desc {
  font-size: 15px;
  color: #666;
}

/* ── Platform Cards ── */

.platforms {
  padding: 36px 0 72px;
}

.platforms-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.platform-card {
  background: #f9fafb;
  border: 1px solid #e5e7eb;
  border-radius: 12px;
  padding: 28px;
  text-align: center;
}

.platform-card h2 {
  font-size: 18px;
  font-weight: 700;
  color: #111;
  margin-bottom: 6px;
}

.platform-version {
  font-size: 13px;
  color: #999;
  margin-bottom: 4px;
}

.platform-req {
  font-size: 13px;
  color: #666;
  margin-bottom: 18px;
}

.platform-card .btn-primary {
  display: block;
  margin-bottom: 6px;
}

.dl-note {
  display: block;
  font-size: 12px;
  color: #999;
  margin-bottom: 14px;
}

.platform-variants {
  display: flex;
  gap: 6px;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
}

.variant-link {
  font-size: 13px;
  color: #2563eb;
  transition: color 0.15s;
}

.variant-link:hover {
  color: #1d4ed8;
  text-decoration: underline;
}

.sep {
  color: #d1d5db;
  font-size: 13px;
}

/* ── Footer ── */

.footer {
  background: #f3f4f6;
  padding: 28px 0;
  text-align: center;
}

.footer p {
  font-size: 13px;
  color: #999;
  line-height: 1.8;
}

/* ── Responsive ── */

@media (max-width: 768px) {
  .hero {
    padding: 48px 0 40px;
  }

  .hero h1 {
    font-size: 24px;
  }

  .hero-desc {
    font-size: 15px;
  }

  .hero-buttons {
    flex-direction: column;
    align-items: center;
  }

  .btn-primary,
  .btn-outline {
    width: 100%;
    max-width: 280px;
    text-align: center;
  }

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

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

  .section-title {
    font-size: 20px;
  }

  .dl-hero h1 {
    font-size: 22px;
  }

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

@media (max-width: 480px) {
  .container {
    padding: 0 16px;
  }

  .hero h1 {
    font-size: 21px;
  }

  .review-card,
  .knowledge-card,
  .platform-card {
    padding: 20px;
  }
}