Check out example codes for "vertical line html". It will help you in understanding the concepts better.

Code Example 1

<!DOCTYPE html>  
<html>  
  
<head>  
    <title>  
        HTML vertical line
    </title>  
      
    <!-- style to create vertical line -->
    <style> 
        .vertical { 
            border-left: 6px solid black; 
            height: 300px; 
            position:absolute; 
            left: 50%; 
        } 
    </style> 
</head> 
  
<body style = "text-align: center;">  
  
    <h1 style = "color: blue;">  
        Testing vertical line  
    </h1>  
          
    <div class = "vertical"></div> 
  
</body>  
  
</html>                                      

Code Example 2

#verticle-line {
  width: 1px;
  min-height: 400px;
  background: red;
}
<div id="verticle-line"></div>

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