body { background-color: #f8f9fa; font-size: 0.95rem; }
    .sync-badge { font-size: 0.8rem; }
    .nav-pills .nav-link { color: #495057; }
    .nav-pills .nav-link.active { background-color: #dc3545; color: white; font-weight: 500; }
    .section-card { border: none; box-shadow: 0 0.125rem 0.25rem rgba(0,0,0,0.075); }
    .form-label { font-weight: 500; font-size: 0.9rem; }
    .input-group-text { background-color: #e9ecef; }
    .form-control, .form-select { border-radius: 0.375rem; }
    @media (max-width: 992px) {
      .sender-receiver-grid > div { margin-bottom: 1.5rem; }
    }