body { background: #f8f9fa; font-family: 'Segoe UI', sans-serif; }
  .vehicle-hero { position: relative; }
  .vehicle-hero img { width: 100%; height: 500px; object-fit: cover; border-radius: 8px; cursor: pointer; }
  .thumb-gallery { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 10px; }
  .thumb-gallery img { width: 80px; height: 60px; object-fit: cover; border-radius: 4px; cursor: pointer; border: 2px solid transparent; transition: border 0.2s; }
  .thumb-gallery img.active { border-color: #0d6efd; }
  .sticky-contact { position: fixed; bottom: 0; left: 0; right: 0; padding: 10px; background: #fff; border-top: 1px solid #ddd; z-index: 1000; }
  footer { background: #1a1f71; color: white; padding: 20px 0; margin-top: 30px; }
  @media (min-width: 768px) { .sticky-contact { position: static; border: none; background: transparent; padding: 0; } }

    #btnBackToTop {
    bottom: 80px;
    right: 20px;
    width: 45px;
    height: 45px;
    display: none; /* ẩn mặc định */
    align-items: center;
    justify-content: center;
    z-index: 999;
    transition: opacity 0.3s ease, transform 0.3s ease;
    }

    #btnBackToTop.show {
    display: flex;
    opacity: 1;
    transform: translateY(0);
    }

    #btnBackToTop.hide {
    opacity: 0;
    transform: translateY(20px);
    }

    #btnBackToTop:hover {
    transform: scale(1.1);
    }