Nav HTML

<nav>
<ul>
<li><a href="#">Home</a></li>
<li><a href="#">Cats</a></li>
<li><a href="#">Dogs</a></li>
<li><a href="#">Fish</a></li>
</ul>
</nav>

Nav CSS

nav ul {
margin: 0;
padding: 0;
list-style-type: none;
}
nav ul li {
margin: 0;
float: left;
}
nav ul li a, nav ul li a:link, nav ul li a:visited {
text-decoration: none;
color: white;
font-size: 16px;
display: block;
box-sizing: border-box;
width: 250px;
height: 50px;
background-color: black;
text-align: center;
padding-top: 15px;
}
nav ul li a:hover, nav ul li a:active {
background-color: orange;
color: black;
}