HTML class Global Attribute - Playground Example

<!DOCTYPE html>
<html>
<head>
   <title>Global class attribute</title>
<style> 
.main {
   text-align:center;
   color:red;
}
.index {
   color:blue;
}
</style>
</head>
<body>
   <h1 class="main">The first level heading.</h1>
   <p class="index">A paragraph with an assigned class.</p>
   <p>A paragraph without an assigned class.</p>
</body>
</html>