CSSとJavaScriptで拡張グリッドを作成するにはどうすればよいですか？

CSSとJavaScriptを使用して拡張グリッドを作成するには、コードは次のとおりです-

例

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1" />
<style>
   body {
      padding: 1%;
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   * {
      box-sizing: border-box;
   }
   .left, .right, .center {
      float: left;
      width: 33%;
      color: white;
      padding: 10px;
      height: 200px;
      text-align: center;
   }
   .left {
      background-color: tomato;
   }
   .right {
      background-color: teal;
   }
   .center {
      background-color: rgb(166, 71, 255);
   }
   .container:after {
      clear: both;
   }
   .closebtn {
      float: right;
      color: white;
      font-size: 35px;
      cursor: pointer;
   }
   .closebtn:hover {
      transform: scale(1.5);
   }
   .containerTab {
      padding: 20px;
      width: 99%;
      color: white;
   }
</style>
</head>
<body>
<h1 style="text-align: center;">Three Column grid example</h1>
<div class="container">
<div class="left" onclick="openTab('tab1');" ;>
<h1>Some text on the left</h1>
</div>
<div class="center" onclick="openTab('tab2');">
<h1>Some text in center</h1>
</div>
<div class="right" onclick="openTab('tab3');">
<h1>Some text on the right</h1>
</div>
</div>
<div id="tab1" class="containerTab" style="display:none;background:tomato">
<span onclick="this.parentElement.style.display='none'" class="closebtn">×</span>
<h2>Tab 1</h2>
<p>
Lorem ipsum dolor sit amet, te quo doctus abhorreant, et pri deleniti intellegat, te sanctus inermis ullamcorper nam. Ius error diceret deseruisse ad
</p>
</div>
<div
id="tab2"
class="containerTab"
style="display:none;background:rgb(166, 71, 255)">
<span onclick="this.parentElement.style.display='none'" class="closebtn">×</span>
<h2>Tab 2</h2>
<p>
Lorem ipsum dolor sit amet, te quo doctus abhorreant, et pri deleniti intellegat, te sanctus inermis ullamcorper nam. Ius error diceret deseruisse ad
</p>
</div>
<div id="tab3" class="containerTab" style="display:none;background:teal">
<span onclick="this.parentElement.style.display='none'" class="closebtn">×</span>
<h2>Tab 3</h2>
<p>
Lorem ipsum dolor sit amet, te quo doctus abhorreant, et pri deleniti intellegat, te sanctus inermis ullamcorper nam. Ius error diceret deseruisse ad
</p>
</div>
<script>
   function openTab(tabName) {
      var i, x;
      x = document.querySelectorAll(".containerTab");
      Array.from(x).forEach(item => {
         item.style.display = "none";
      });
      document.getElementById(tabName).style.display = "block";
   }
</script>
</body>
</html>