My background color for my is not working

So I want to make my background #22223b, however my code is not working?

Some HTML

        <div class="nav">
            <ul>
                <li> <a href="index.html">Home</a> </li>
                <li> <a href="#">About Us</a> </li>
                <li> <a href="#">Start Learning</a> </li>
            </ul>
        </div>
        <div class="account">
            <ul>
                <li> <a href="#">Profile</a> </li>
                <li> <a href="#">Portal</a> </li>
            </ul>
        </div>```

Some CSS

.nav{
    background-color: #22223b;
}