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HTML 

              
                <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Understanding CSS: visibility hidden vs display none</title>

</head>
<body>
    <h1>Understanding CSS: visibility hidden vs display none</h1>
    <div id="container">
        <div id="left">
            <div>
                <p>When it comes to hide HTML content to the client</p> 
                <p>visibility: hidden and display: none. </p>
            </div>
            <div>
                <p>These two rules are not synonyms, no:</p> 
                <ul>
                    <li>visibility: hidden means that the element won't be visible but the space is allocated</li>
                    <li>display: none unlike the first one means the element will</li>
                </ul>
            </div>
            <div>
                <p>The DNA strand is missing the pairing element.</p> 
                <p>For example, for the input GCG, return [["G", "C"], ["C","G"],["G", "C"]]</p>
            </div>  
            <div>
                <p>Our goal of this exercice is to <span>return the missing trand</span>  into a 2d array</p> 
                <p>Some people think they are just synonyms, others are just confused </p>
            </div>
                      
        </div>
        <div id="right">
            <div class="vh">
                <p>When it comes to hide HTML content to the client</p> 
                <p>visibility: hidden and display: none. </p>
                </div>
                <div>
                    <p>These two rules are not synonyms, no:</p> 
                    <ul>
                        <li>visibility: hidden means that the element won't be visible but the space is allocated</li>
                        <li>display: none unlike the first one means the element will</li>
                    </ul>
                </div>
                <div class="dn">
                    <p>The DNA strand is missing the pairing element.</p> 
                    <p>For example, for the input GCG, return [["G", "C"], ["C","G"],["G", "C"]]</p>
                </div>
                <div>
                    <p>Our goal of this exercice is to <span class="vh">return the missing trand</span>  into a 2d array</p> 
                    <p>Some people think they are just synonyms, others are just confused </p>
                </div>
                
        </div>
    </div>
</body>
</html>
!

CSS 

              
                 #container {
            display: flex;
            justify-content: space-between;
            width: 71em;
        }

        #left,
        #right {
            width: 35em;

        }

        #left div:first-child,
        #right div:first-child {
            background: olivedrab;
        }

        #left div:nth-child(2),
        #right div:nth-child(2) {
            background: orange;
        }

        #left div:nth-child(3),
        #right div:nth-child(3) {
            background:cadetblue;
        }

        #left div:last-child,
        #right div:last-child {
            background:orchid;
        }

        .vh {
            visibility: hidden;
        }

        .dn {
            display: none;
        }
!

JS
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