#clock {
    flex: 1 1 300px;
    max-width: 800px;
    display: flex;
    justify-content: center;
    align-items: center;
  }
  
canvas {
    width: 100vw;
    height: 100vw;
    max-width: 800px;
    max-height: 800px;
}

  /* xsm */
  @media (min-width: 411px) {
    canvas {
      max-width: 420px;
      max-height: 420px;
    }    
  }

  /* sm */
  @media (min-width: 576px) {

  }

  /* md */
  @media (min-width: 768px) {
    canvas {
      max-width: 500px;
      max-height: 500px;
    }

  }

  /* lg */
  @media (min-width: 992px) {
    
  }

  /* xl */
  @media (min-width: 1200px) {

  }

  /* xxl */
  @media (min-width: 1400px) {
    canvas {
      max-width: 800px;
      max-height: 800px;
    }
  }