/* === Reset & Base === */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
:root {
  --color-bg: #ffffff;
  --color-bg-alt: #f5f5f7;
  --color-bg-dark: #1d1d1f;
  --color-text: #1d1d1f;
  --color-text-secondary: #6e6e73;
  --color-text-light: #f5f5f7;
  --color-accent: #0071e3;
  --color-accent-hover: #0077ed;
  --color-border: #d2d2d7;
  --font-primary: -apple-system, BlinkMacSystemFont, "SF Pro SC", "SF Pro Text", "SF Pro Icons", "PingFang SC", "Helvetica Neue", "Microsoft YaHei", sans-serif;
  --max-width: 1200px;
  --nav-height: 48px;
  --radius: 12px;
  --radius-sm: 8px;
}
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-primary);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--color-accent); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; height: auto; display: block; }
ul, ol { list-style: none; }

/* === Layout === */
.container { max-width: var(--max-width); margin: 0 auto; padding: 0 24px; }
.section { padding: 80px 0; }
.section-alt { background: var(--color-bg-alt); }

/* === Header / Nav === */
.site-header {
  position: sticky; top: 0; z-index: 999;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--color-border);
  height: var(--nav-height);
}
.site-header .container {
  display: flex; align-items: center; justify-content: space-between;
  height: var(--nav-height);
}
.nav-logo img { height: 32px; width: auto; }
.nav-links { display: flex; gap: 32px; }
.nav-links a {
  font-size: 14px; color: var(--color-text); text-decoration: none;
  transition: color 0.2s;
}
.nav-links a:hover { color: var(--color-accent); }
.nav-toggle { display: none; background: none; border: none; cursor: pointer; }
.nav-toggle span { display: block; width: 20px; height: 2px; background: var(--color-text); margin: 4px 0; transition: 0.3s; }

/* === Hero === */
.hero {
  padding: 120px 0 80px; text-align: center;
  background: var(--color-bg);
}
.hero h1 {
  font-size: clamp(32px, 5vw, 56px);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}
.hero h1 span { color: var(--color-accent); }
.hero .subtitle {
  font-size: clamp(16px, 2vw, 21px);
  color: var(--color-text-secondary);
  max-width: 640px; margin: 0 auto 32px;
}
.hero .btn-group { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }
.btn {
  display: inline-block; padding: 12px 28px;
  border-radius: 980px; font-size: 16px; font-weight: 500;
  cursor: pointer; border: none; text-decoration: none;
  transition: all 0.2s;
}
.btn-primary { background: var(--color-accent); color: #fff; }
.btn-primary:hover { background: var(--color-accent-hover); text-decoration: none; }
.btn-secondary { background: transparent; color: var(--color-accent); border: 1px solid var(--color-accent); }
.btn-secondary:hover { background: var(--color-accent); color: #fff; text-decoration: none; }

/* === Metrics === */
.metrics { display: grid; grid-template-columns: repeat(4, 1fr); gap: 32px; text-align: center; }
.metrics .metric-value {
  font-size: 48px; font-weight: 700; color: var(--color-accent);
  line-height: 1; margin-bottom: 8px;
}
.metrics .metric-label { font-size: 14px; color: var(--color-text-secondary); }

/* === Cards === */
.card-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.card {
  background: var(--color-bg); border-radius: var(--radius);
  overflow: hidden; transition: transform 0.3s, box-shadow 0.3s;
  border: 1px solid var(--color-border);
}
.card:hover { transform: translateY(-4px); box-shadow: 0 12px 40px rgba(0,0,0,0.08); }
.card-img { width: 100%; height: 200px; object-fit: cover; background: var(--color-bg-alt); }
.card-body { padding: 24px; }
.card-body h3 { font-size: 20px; margin-bottom: 8px; }
.card-body p { font-size: 14px; color: var(--color-text-secondary); margin-bottom: 16px; }
.card-link { font-size: 14px; font-weight: 500; }

/* === Partners === */
.partners { display: flex; gap: 48px; justify-content: center; align-items: center; flex-wrap: wrap; }
.partners img { height: 48px; opacity: 0.7; }

/* === Footer === */
.site-footer {
  background: var(--color-bg-dark); color: var(--color-text-secondary);
  padding: 48px 0 24px; font-size: 13px;
}
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 48px; margin-bottom: 40px; }
.footer-grid h4 { color: var(--color-text-light); font-size: 14px; margin-bottom: 16px; }
.footer-grid a { color: var(--color-text-secondary); font-size: 13px; }
.footer-grid a:hover { color: var(--color-text-light); text-decoration: none; }
.footer-bottom { border-top: 1px solid #424245; padding-top: 24px; display: flex; justify-content: space-between; flex-wrap: wrap; }

/* === Page Header === */
.page-header {
  padding: 80px 0 48px; text-align: center; border-bottom: 1px solid var(--color-border);
}
.page-header h1 { font-size: clamp(28px, 4vw, 44px); font-weight: 700; margin-bottom: 12px; }
.page-header p { font-size: 18px; color: var(--color-text-secondary); max-width: 600px; margin: 0 auto; }

/* === Product Detail === */
.product-detail { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: center; padding: 60px 0; }
.product-visual { background: var(--color-bg-alt); border-radius: var(--radius); padding: 48px; min-height: 320px; display: flex; align-items: center; justify-content: center; }
.product-visual strong { font-size: 24px; color: var(--color-text-secondary); }
.product-info h2 { font-size: 32px; margin-bottom: 16px; }
.product-info p { margin-bottom: 16px; color: var(--color-text-secondary); }
.feature-list { margin: 24px 0; }
.feature-list li { padding: 8px 0; font-size: 15px; }
.feature-list li::before { content: "\2713"; margin-right: 12px; color: var(--color-accent); }

/* === News Detail === */
.article-detail { max-width: 720px; margin: 48px auto; }
.article-detail h1 { font-size: 32px; margin-bottom: 12px; line-height: 1.2; }
.article-meta { font-size: 14px; color: var(--color-text-secondary); margin-bottom: 32px; }
.article-content p { margin-bottom: 16px; font-size: 16px; line-height: 1.8; }

/* === About / Contact === */
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: center; }
.about-text h2 { font-size: 28px; margin-bottom: 16px; }
.about-text p { margin-bottom: 12px; color: var(--color-text-secondary); }
.contact-form { max-width: 560px; margin: 0 auto; }
.form-group { margin-bottom: 20px; }
.form-group label { display: block; font-size: 14px; margin-bottom: 6px; }
.form-group input, .form-group textarea {
  width: 100%; padding: 12px; border: 1px solid var(--color-border);
  border-radius: var(--radius-sm); font-size: 15px; font-family: inherit;
}
.form-group textarea { resize: vertical; min-height: 120px; }

/* === Mobile === */
@media (max-width: 768px) {
  .nav-links { display: none; }
  .nav-links.active { display: flex; flex-direction: column; position: absolute; top: var(--nav-height); left: 0; right: 0; background: var(--color-bg); padding: 24px; gap: 20px; border-bottom: 1px solid var(--color-border); }
  .nav-toggle { display: block; }
  .metrics { grid-template-columns: repeat(2, 1fr); gap: 24px; }
  .card-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
  .product-detail { grid-template-columns: 1fr; }
  .about-grid { grid-template-columns: 1fr; }
  .section { padding: 48px 0; }
  .hero { padding: 80px 0 48px; }
}
@media (max-width: 480px) {
  .metrics { grid-template-columns: 1fr 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
}