fractional_unit.html

<!DOCTYPE html>
<html>
  <head>
    <title>CSS Grid</title>
    <style>
      body {
        margin-top: 40px;
      }

      #container {
        width: 800px;
        margin: auto;
        background: #e3e3e3;

        display: grid;
        /* grid-template-columns: 100px 100px 1fr; */
        /* grid-template-columns: 100px 2fr 1fr; */
        grid-template-columns: repeat(3, 1fr);
        /* grid-template-columns: repeat(3, 100px); */
        grid-template-rows: repeat(3, 50px);
        grid-gap: 1em;
      }

      #container > div {
        background: #999;
        font-weight: bold;
        color: white;
        font-family: sans-serif;
      }

    </style>
  </head>
  <body>
    <section id="container">
      <div>1</div>
      <div>2</div>
      <div>3</div>
      <div>4</div>
      <div>5</div>
      <div>6</div>
      <div>7</div>
      <div>8</div>
      <div>9</div>
    </section>
  </body>
</html>