example.html

<html>
    <head>
        <link rel="stylesheet" href="app.css" />
    </head>
    <body>
        <div class="content">
            <div class="content__block">
                <span>1</span>
            </div>
            <div class="content__block">
                <span>2</span>
            </div>
            <div class="content__block">
                <span>3</span>
            </div>
            <div class="content__block">
                <span>4</span>
            </div>
        </div>
    </body>
</html>