/* ==========================================================================
   宁达(NIDA)科技网 - 响应式适配
   ========================================================================== */

/* ---------- 大屏以下 ---------- */
@media (max-width: 1100px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .hero h1 { font-size: 44px; }
  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }
}

/* ---------- 平板 ---------- */
@media (max-width: 900px) {
  .section { padding: 64px 0; }
  .section-head h2 { font-size: 28px; }
  .section-head { margin-bottom: 40px; }

  /* 移动端导航 */
  .nav-toggle { display: flex; }
  .main-nav {
    position: fixed; top: var(--header-h); left: 0; right: 0;
    background: #fff; flex-direction: column; align-items: stretch; gap: 0;
    padding: 16px 24px 24px; box-shadow: var(--shadow); border-top: 1px solid var(--border);
    transform: translateY(-130%); transition: transform .35s; max-height: calc(100vh - var(--header-h)); overflow-y: auto;
  }
  .main-nav.open { transform: translateY(0); }
  .main-nav a { padding: 14px 12px; border-radius: 0; border-bottom: 1px solid var(--border); font-size: 16px; }
  .main-nav a:hover { background: var(--brand-soft); }
  .main-nav .nav-cta { margin: 12px 0 0; text-align: center; border-radius: var(--radius-sm); border-bottom: none; }

  /* Hero */
  .hero { min-height: auto; padding: calc(var(--header-h) + 50px) 0 60px; }
  .hero h1 { font-size: 34px; }
  .hero .lead { font-size: 17px; }
  .hero-content { flex-direction: column; gap: 32px; }
  .hero-content .hero-image { width: 100%; max-width: 450px; }
  .hero-stats { gap: 32px; margin-top: 44px; flex-wrap: wrap; }
  .hero-stats .stat .num { font-size: 30px; }

  /* 页面 hero */
  .page-hero h1 { font-size: 30px; }
  .page-hero p { font-size: 16px; }

  /* 网格变单/双列 */
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .grid-4 { grid-template-columns: 1fr 1fr; }

  /* 图文交替变上下 */
  .split { grid-template-columns: 1fr; gap: 32px; }
  .split.reverse .split-text { order: 0; }

  /* 画廊/视频 */
  .gallery, .video-grid { grid-template-columns: 1fr 1fr; }

  /* 联系页 */
  .contact-grid { grid-template-columns: 1fr; gap: 36px; }
  .map-wrap { height: 320px; }

  /* 关于页 */
  .about-intro { grid-template-columns: 1fr; gap: 36px; }

  /* CTA */
  .cta-banner { padding: 40px 32px; flex-direction: column; text-align: center; }
  .cta-banner h2 { font-size: 24px; }

  /* 表单 */
  .form-card { padding: 32px 24px; }
  .form-row { grid-template-columns: 1fr; gap: 0; }

  /* 下载卡片 */
  .dl-card { flex-direction: column; text-align: center; gap: 16px; }
}

/* ---------- 手机 ---------- */
@media (max-width: 600px) {
  .container { padding: 0 18px; }
  .section { padding: 52px 0; }
  .section-head h2 { font-size: 25px; }
  .section-head p { font-size: 15px; }

  .hero h1 { font-size: 28px; }
  .hero .lead { font-size: 16px; }
  .hero-content .hero-image { display: none; }
  .hero-actions { flex-direction: column; }
  .hero-actions .btn { width: 100%; }
  .hero-stats { gap: 24px; }
  .hero-stats .stat .num { font-size: 26px; }

  .grid-4, .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .gallery, .video-grid { grid-template-columns: 1fr; }

  .page-hero { padding: calc(var(--header-h) + 50px) 0 50px; }
  .page-hero h1 { font-size: 26px; }

  .footer-grid { grid-template-columns: 1fr; gap: 28px; }

  .brand-text { font-size: 16px; }
  .brand-text small { font-size: 10px; }
  .brand img { height: 38px; }

  .cta-banner { padding: 32px 22px; }
  .cta-banner h2 { font-size: 21px; }
  .cta-banner .btn { width: 100%; }

  .compare-table { font-size: 13px; }
  .compare-table th, .compare-table td { padding: 11px 10px; }

  .form-card { padding: 26px 18px; }

  .to-top { right: 18px; bottom: 18px; width: 42px; height: 42px; }
}