Circles Animating in Size

Inspired by a Bees and Bombs classic.

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<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Circle Big Size</title>
  </head>
  <body>
    <style>
      svg {
        position: absolute;
        left: 50%;
        top: 50%;
        transform: translate(-50%, -50%);
        background-color: #d3d3d3; }
    </style>
    <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.4.4/d3.min.js"></script>
    <script type="text/javascript" src="script.js"></script>
  </body>
</html>
    

https://cdnjs.cloudflare.com/ajax/libs/d3/4.4.4/d3.min.js