body, html{
    margin: 0;
    height: 100vh;
    background: linear-gradient(-45deg, #204, #000);
    overflow: hidden;
  }
  #c:focus{
    outline: none;
  }
  #c{
    border: 3px solid #0Ff3;
    position: absolute;
    background: #04f1;
    left: 50%;
    top: 50%;
    border-radius: 10px;
    transform: translate(-50%, -50%);
  }