.demo {
  text-align: center;

  .demo-header {
    background-color: #203957;
    height: 150px;
    padding: 20px;
    color: white;

    .demo-logo {
      animation: demo-logo-spin infinite 20s linear;
      height: 80px;
    }

    @keyframes demo-logo-spin {
      from { transform: rotate(0deg); }
      to { transform: rotate(360deg); }
    }
  }

  .demo-introduce {
    font-size: large;
  }
}
