body {
  margin:0;
  position:relative;
}
.logo {
  position:absolute;
  top:50%;
  left:50%;
  transform:translate(-50%, -50%);
  width:90%;
}
.logo img {
  width:100%;
}
canvas {
  display: block;
  width: 100%;
  height: 100vh;
}

@media (min-width:768px) {

  canvas {
    display: block;
    width: 100vw;
    height: 100vh;
  }
  .logo {
    width:auto;
  }
  .logo img {
    width:500px;
  }

}