center svg

help to center svg

HTML

<div id="svg-container">
  <svg id="svg-1" height="50%" width="50%" viewBox="0 0 1000 1000" xmlns="http://www.w3.org/2000/svg" version="1.1">
     <circle r="15" cx="350" cy="80"></circle>
  </svg>
</div>

CSS

#svg-container
{
  background-color: red;
}

#svg-1
{
  margin: auto auto;
  display: block;
  height: 30%;
}