W3Schools Tryit Editor

<!DOCTYPE html>
<html>
<head>
<style>
* {
  box-sizing: border-box;
}

body {
  font-family: Arial, Helvetica, sans-serif;
}

/* Style the header */
.header {
  grid-area: header;
  background-color: #f1f1f1;
  padding: 30px;
  text-align: center;
  font-size: 35px;
}

/* The grid container */
.grid-container {
  display: grid;
  grid-template-areas: 
    'header header header header header header' 
    'left left middle middle right right' 
    'footer footer footer footer footer footer';
  /* grid-column-gap: 10px; - if you want gap between the columns */
}

.left,
.middle,
.right {
  padding: 10px;
  height: 300px; /* Should be removed. Only for demonstration */
}

/* Style the left column */
.left {
  grid-area: left;
}

/* Style the middle column */
.middle {
  grid-area: middle;
}

/* Style the right column */
.right {
  grid-area: right;
}

/* Style the footer */
.footer {
  grid-area: footer;
  background-color: #f1f1f1;
  padding: 10px;
  text-align: center;
}

/* Responsive layout - makes the three columns stack on top of each other instead of next to each other */
@media (max-width: 600px) {
  .grid-container  {
    grid-template-areas: 
      'header header header header header header' 
      'left left left left left left' 
      'middle middle middle middle middle middle' 
      'right right right right right right' 
      'footer footer footer footer footer footer';
  }
}
</style>
</head>
<body>

<h2>CSS Template using Grid</h2>
<p>In this example, we have created a header, three equal columns and a footer. On smaller screens, the columns will stack on top of each other.</p>
<p>Resize the browser window to see the responsive effect.</p>
<p><strong>Note:</strong> The Grid Layout Module is not supported in Internet Explorer or Edge 15 eand earlier versions.</p>

<div class="grid-container">
  <div class="header">
    <h2>Header</h2>
  </div>
  
  <div class="left" style="background-color:#aaa;">Column</div>
  <div class="middle" style="background-color:#bbb;">Column</div>  
  <div class="right" style="background-color:#ccc;">Column</div>
  
  <div class="footer">
  <p>Footer</p>
  </div>
</div>

</body>
</html>

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<!DOCTYPE html><html><head><style>* {  box-sizing: border-box;}​body {  font-family: Arial, Helvetica, sans-serif;}​/* Style the header */.header {  grid-area: header;  background-color: #f1f1f1;  padding: 30px;  text-align: center;  font-size: 35px;}​/* The grid container */.grid-container {  display: grid;  grid-template-areas:     'header header header header header header'     'left left middle middle right right'     'footer footer footer footer footer footer';  /* grid-column-gap: 10px; - if you want gap between the columns */} ​.left,.middle,.right {  padding: 10px;  height: 300px; /* Should be removed. Only for demonstration */}​/* Style the left column */.left {  grid-area: left;}​/* Style the middle column */.middle {