sketch.html

<!DOCTYPE html>
<html>
  <head>
    <style>
      body {
        display: flex;
        align-items: center;
        justify-content: center;
        background: #FAFAFA;
      }
      canvas {
        background: #FFFFFF;
      }
    </style>
    <meta charset="utf-8">
  </head>
  <body>
    <main></main>
    <script src="https://unpkg.com/elm-canvas@2.2/elm-canvas.js"></script>
    <script src="sketch.js"></script>
    <script>
      // Usually you do `Elm.main.init({...})`, but every module has a different
      // name, and we want to reuse this template with elm-live.
      // Since everything is organised as <chapter>/<sketch>, we run init of
      // the first nested object.
      var firstProperty = (o) => o[Object.keys(o)[0]];
      var module = firstProperty(firstProperty(Elm));
      var app = module.init({ node: document.querySelector("main") });
    </script>
  </body>
</html>