body {
margin: 0;
}

#canvas1 {
  padding-left: 0;
  padding-right: 0;
  margin-top: 5px;
  margin-left: auto;
  margin-right: auto;
  display: block;
  width: 1200px;
  border: 2px solid darkgreen;
  background: darkgreen;
}

@media only screen and (max-width: 1100px) {
  #canvas1 {
    max-width: 800px;
    max-height: 800px;
  }
}

@media only screen and (max-width: 800px) {
  #canvas1 {
    max-width: 500px;
    max-height: 500px;
  }
}