classes.html

<!DOCTYPE html>
<html lang="en">
<head>
    <style>
.city
{
    background-color: chartreuse;
    color: wheat;
    padding: 20px;
    margin: 30px;
    border: solid 20px;
}

    </style>
    <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>Document</title>
</head>
<body>
    <!-----div tag-->
<div class="city">
<h2>London</h2>
<p>London is the capital of England.</p>
</div>
<div class="city">
    <h2>Paris</h2>
    <p>Paris is the capital of France.</p>
    </div>
    <div class="city">
        <h2>Newyork</h2>
        <p>Newyork is the capital of America.</p>
        </div>
<!----Span tag in the class in div tag-->
<style>
.note
{
 font-size: 120px;
 color: rebeccapurple;
}
</style>
<h1> <span class="note">Important</span>Heading</h1>
<p>this is a paragraph<span class="note">Important</span>Heading</p>
</body>
</html>