body {
  background: url('images/us-flag-bg.jpg') no-repeat center center fixed;
  background-size: cover;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  color: #fff;
  margin: 0;
  padding: 0;
}

.card, .table, .form-control, .btn {
  border-radius: 0.5rem;
}

.card-body {
  background-color: rgba(0, 0, 0, 0.75);
  color: #fff;
}

.table th, .table td {
  vertical-align: middle;
}

.navbar {
  background-color: rgba(0, 0, 0, 0.85) !important;
  border-bottom: 2px solid #28a745;
}

.navbar-brand {
  font-weight: bold;
  font-size: 1.25rem;
}

.alert {
  font-size: 0.9rem;
}

/* Responsive tweaks */
@media (max-width: 768px) {
  .card {
    margin-top: 1rem;
  }

  h1, .card-title {
    font-size: 1.5rem;
    text-align: center;
  }

  .table {
    font-size: 0.9rem;
  }

  .form-control, .btn {
    font-size: 0.9rem;
  }
}

@media (max-width: 576px) {
  .container {
    padding-left: 10px;
    padding-right: 10px;
  }

  .navbar-brand {
    font-size: 1rem;
  }

  .nav-link {
    font-size: 0.9rem;
  }
}