Prova tu stesso - W3.CSS navbar

<!DOCTYPE html>
<html>
<title>W3.CSS</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="/lib/w3.css">
<body class="w3-container">

<h2>Navigation Bar Sizes</h2>
Add the w3-padding-classes to change the padding of each link inside the navbar.

Default:
<ul class="w3-navbar w3-green">
 <li><a href="#">Home</a></li>
 <li><a href="#">Link 1</a></li>
 <li><a href="#">Link 2</a></li>
</ul>

w3-padding-hor-16:
<ul class="w3-navbar w3-green">
 <li><a class="w3-padding-hor-16" href="#">Home</a></li>
 <li><a class="w3-padding-hor-16" href="#">Link 1</a></li>
 <li><a class="w3-padding-hor-16" href="#">Link 2</a></li>
</ul>

w3-padding-hor-24:
<ul class="w3-navbar w3-green">
 <li><a class="w3-padding-hor-24" href="#">Home</a></li>
 <li><a class="w3-padding-hor-24" href="#">Link 1</a></li>
 <li><a class="w3-padding-hor-24" href="#">Link 2</a></li>
</ul>

w3-padding-hor-32:
<ul class="w3-navbar w3-green">
 <li><a class="w3-padding-hor-32" href="#">Home</a></li>
 <li><a class="w3-padding-hor-32" href="#">Link 1</a></li>
 <li><a class="w3-padding-hor-32" href="#">Link 2</a></li>
</ul>

Note: You can also add padding to the navbar, instead of each link. However, if you do this, note that the links do not get full padding on hover:
<ul class="w3-navbar w3-green w3-padding-hor-16">
 <li><a href="#">Home</a></li>
 <li><a href="#">Link 1</a></li>
 <li><a href="#">Link 2</a></li>
</ul>

</body>
</html>