<html>
<title>W3.CSS</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://www.w3schools.com/w3css/4/w3.css">
<body>
<div class="w3-container">
<h2>Circular Buttons</h2>
<button class="w3-button w3-xlarge w3-circle w3-black">+</button>
<button class="w3-button w3-xlarge w3-circle w3-teal">+</button>
<button class="w3-button w3-xlarge w3-circle w3-red w3-card-4">+</button>
</div>
</body>
</html>