<html lang="en">
<head>
    <link rel="stylesheet" href="pages/index.css">
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Domstroy</title>
</head>
<body class="body">
    <header class="header">
        <div class="header__logo"><img src="images/home.png" alt="" class="header__logo_img"></div>
        <div class="header__title"></div>
        <div class="header__number"></div>
        <div class="header__mail"></div>
    </header>
<div class="main" onclick="chengeClass(this);">
    
     click me     
</div>
     <footer class="footer">
        <div class="footer__number"></div>
        <div class="footer__mail"></div>
    </footer> 
</body>
</html>

.main{
    background-color: brown;
    height: 200px;
    width: 100%;
    z-index:1;
    margin:auto;
    cursor:pointer;
    display:flex;
    align-items: center;
    justify-content: center;
}
.modifed{
  background-color: green;
  width: 75%;
  margin:auto;
}
chengeClass = (element) => {
  element.classList.toggle('modifed');
}

External CSS

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External JavaScript

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