I was so impressed when I saw how the previous page made it so much easier to get the overall picture that I've decided to go one step further and show you how to have your CSS in a separate file also.

styles.css
.row {
  display:flex;
  align-items:center;
}
.cell {
  height:13vmin;
  border:thin solid;
}

And seeing we've come this far, maybe it's time to introduce the tags that we should have been using all the time: <html>, <head>, <title> and <body>.

index.html
<html>
<head>
  <title>Yahtzee Solitaire</title>
  <link rel='stylesheet' href='styles.css'>
  <script src='one_row.js'></script>
  <script src='cell_clicked.js'></script>
</head>
<body>
  <div class='row'>
    <script>one_row();</script>
  </div>
</body>
</html>