Css Grid: fractional units

<!DOCTYPE html>
<html>

  <head>
    <link rel="stylesheet" href="style.css">
    <script src="script.js"></script>
  </head>

  <body>
   <div class="container">
   <div class="box a">A</div>
   <div class="box b">B</div>
   <div class="box c">C</div>
   <div class="box d">D</div>
   <div class="box e">E</div>
  </body>

</html>

// Code goes here

/* Styles go here */

.container{
  display:grid;
  height:100vh;
  grid-gap:10px;
  
  grid-template-rows: 1fr 3fr;
  
  grid-template-columns: 1fr 2fr 1fr;
}

.box {
  background-color: dodgerblue;
  font-size: 30px;
}