mozilla-release/layout/reftests/css-grid/grid-placement-definite-001.html

<!DOCTYPE HTML>
<html><head>
    <meta charset="utf-8">
    <title></title>
    <style type="text/css">

.grid {
 display: grid;
 grid-template-areas:
'. . a a a .'
'. . a a a .'
'. b b . . .'
;
  border: 10px solid green;
  grid-template-columns: 20px 20px 20px 20px;
  grid-template-rows: 20px 20px 20px;
  grid-auto-flow: column dense;
  grid-auto-columns: 20px;
  grid-auto-rows: 20px;
  font-size:12px;
}

span {
  background: lime;
  border: 1px solid black;
}

.a {
  grid-area: a;
}
.b {
  grid-column: 2 / span 3; 
  grid-row: b;
}
.c {
  grid-column: span 3;
}
.d {
  grid-row: span 3;
}
    </style>
</head>
<body>

<div class=grid>
<span class=a>a</span>
<span class=b>b</span>
<span class=c>c</span>
<span class=d>d</span>
</div>

</body>
</html>