Specific background for single nav link - html

Question

Looking to find out how to change a single nav link to have a different background hover color than the others.
I've tried #nav #contact.hover and #nav #contact:hover to no avail.
<div id="nav">
<ul>
<li id="home">Home</li>
<li id="service">Service</li>
<li id="parts">Parts</li>
<li id="contact">Contact</li>
</ul>
<div class="clearall"></div>
</div>
</html>
CSS:
.clearall {
clear:both;
}
#nav {
background:#333;
}
#nav ul li {
float:left;
margin-right:0px;
}
#nav ul li a {
color:#fff;
text-transform:uppercase;
padding:10px 20px;
display:block;
text-decoration:none;
}
#nav ul li a:hover {
background-color:black;
}
Should change the contact element in the nav to have a background hover color of white

Answer 1

Just have to get the selector right. I think you were having issues because your base style for hover is overly specific which trumps most overrides.
#nav ul li:hover a
...could easily be changed to simpler selector that would be easier to override, the use of ID's instead of classes adds to the specificity issue as well.
.clearall {
clear:both;
}
#nav {
background:#333;
}
#nav ul li {
float:left;
margin-right:0px;
}
#nav ul li a {
color:#fff;
text-transform:uppercase;
padding:10px 20px;
display:block;
text-decoration:none;
}
#nav ul li:hover a {
background-color:black;
}
#nav ul li#contact:hover a {
background: url('https://picsum.photos/100');
}
<div id="nav">
<ul>
<li id="home">Home</li>
<li id="service">Service</li>
<li id="parts">Parts</li>
<li id="contact">Contact</li>
</ul>
<div class="clearall"></div>
</div>

Answer 2

You can accomplish this by using the :last-child psuedo-class in your CSS.
Here's a codepen with the fix but I'll describe below what I did: https://codepen.io/Athys/pen/WBdYdZ
I added :last-child to the li selector since the "contact" link appears as the last list item (the last li). Then, I added a :hover psuedo-class to the a selector and give it a different hover color and text-color than the other a elements. Hope this helps.