Live Demo - CSS 3 Flex Order

Source Code

<!DOCTYPE html>
  <html lang="en">
    <head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>CSS Flex </title>
	 <style> 
     .flex-container {
       display: flex;
       flex-direction:row;
       background-color:lightgray;
       height:120px;
        }
     .flex-item{
       background-color:orange;
        color:white;
        text-align:center;
        height:80px;
        width:80px;
        line-height:80px;
        margin:10px;
        padding:10px;
      }
      .bg-info{
        background-color:#17A2B8;
      }
      
      .bg-primary{
        background-color:#007BFF;
      }
      
      .bg-warning{
        background-color:#FFC107;
      }
     </style>
</head>
<body>   
        <h1>The order Property</h1>  
        <div class="flex-container">
          <div class="flex-item" style="order: 3">1</div>
          <div class="flex-item" style="order: 2">2</div>
          <div class="flex-item" style="order: 4">3</div>
          <div class="flex-item" style="order: 1">4</div>
        </div>
</body>
</html>
Source Code

Source Code Output :Running
