/* ===== 响应式样式 ===== */

/* 大屏 */
@media (max-width: 1200px) {
  .container { max-width: 100%; }
}

/* 平板 */
@media (max-width: 992px) {
  .products-grid { grid-template-columns: repeat(2, 1fr); }
  .about-grid { grid-template-columns: 1fr; gap: 36px; }
  .about-image { order: -1; }
  .about-img-placeholder { height: 280px; }
  .why-grid { grid-template-columns: repeat(2, 1fr); }
  .cases-grid { grid-template-columns: repeat(2, 1fr); }
  .news-grid { grid-template-columns: 1fr 1fr; }
  .news-card.featured { grid-column: span 2; }
  .contact-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .stat-item { border-right: none; border-bottom: 1px solid rgba(255,255,255,0.15); }
  .stat-item:nth-child(2n) { border-bottom: none; }
}

/* 手机 */
@media (max-width: 768px) {
  .section { padding: 52px 0; }
  .section-title { font-size: 1.6rem; }
  .banner { height: 420px; }
  .banner-content h1, .banner-content h2 { font-size: 1.8rem; }
  .banner-icon { display: none; }
  .banner-item { padding: 0 30px; }

  /* 移动导航 */
  .nav { display: none; position: fixed; top: 72px; left: 0; right: 0; background: #fff; box-shadow: 0 8px 24px rgba(0,0,0,0.12); padding: 16px 0; z-index: 999; max-height: calc(100vh - 72px); overflow-y: auto; }
  .nav.open { display: block; }
  .nav > ul { flex-direction: column; gap: 0; }
  .nav > ul > li > a { padding: 14px 24px; border-radius: 0; border-bottom: 1px solid #f0f0f0; }
  .sub-menu { position: static; box-shadow: none; border-top: none; border-left: 3px solid var(--accent); margin-left: 24px; display: block; background: #fafafa; border-radius: 0; }
  .sub-menu li a { padding: 10px 18px; }
  .nav-toggle { display: flex; }

  .top-bar { display: none; }
  .products-grid { grid-template-columns: 1fr; }
  .why-grid { grid-template-columns: 1fr; }
  .cases-grid { grid-template-columns: 1fr; }
  .news-grid { grid-template-columns: 1fr; }
  .news-card.featured { grid-column: span 1; }
  .footer-grid { grid-template-columns: 1fr; }
  .footer-bottom-content { flex-direction: column; text-align: center; }
  .form-row { grid-template-columns: 1fr; }
  .contact-form { padding: 24px 16px; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .banner-btns { flex-direction: column; gap: 10px; }
  .btn-primary, .btn-outline, .btn-secondary { padding: 10px 22px; font-size: 14px; }
  .more-link { position: static; display: block; margin-top: 8px; }
  .section-header { position: relative; }
  .partners-row { gap: 10px; }
  .partner-item { min-width: 130px; }
}

@media (max-width: 480px) {
  .banner { height: 360px; }
  .banner-content h1, .banner-content h2 { font-size: 1.4rem; }
  .stat-number { font-size: 1.8rem; }
  .back-to-top { bottom: 16px; right: 16px; }
}