html,body{
    margin: 0;
    padding: 0;
    background-color: black;
}
svg.container{
    position:relative;
      display:block;
    margin:auto;
    width:100vw;
    height:100vh;
}

svg.group
{
    transform: translate(-50%, -50%)
}

circle.visible{
    visibility: visible;
}

circle.hidden{
    visibility: hidden;
}