A CodePen by Liam. CSS Menu Live Practice

index.html

<p><a href="http://line25.com/tutorials/how-to-create-a-pure-css-dropdown-menu">Tutorial Link</a>

<nav>
	<ul>
		<li><a href="#">One</a></li>
		<li><a href="#">Two</a>
			<ul>
				<li><a href="#">TWO TWO</a></li>
				<li><a href="#">TWO THREE</a>
					<ul>
						<li><a href="#">two two</a></li>
						<li><a href="#">two three</a></li>
					</ul>
				</li>
			</ul>
		</li>
		<li><a href="#">Three</a></li>
		<li><a href="#">Four</a></li>
	</ul>
		
</nav>

style.css

nav ul ul {
	display: none;
}

nav ul li:hover > ul {
	display: block;
}

nav ul {
	background: #efefef; 
	background: linear-gradient(top, #efefef 0%, #bbbbbb 100%);  
	background: -moz-linear-gradient(top, #efefef 0%, #bbbbbb 100%); 
	background: -webkit-linear-gradient(top, #efefef 0%,#bbbbbb 100%); 
	box-shadow: 0px 0px 9px rgba(0,0,0,0.15);
	padding: 0 20px;
	border-radius: 10px;  
	list-style: none;
	position: relative;
	display: inline-table;
}

nav ul:after {
		content: "";
    clear: both;
    display: block;
}

nav ul li {
	float: left;
}

nav ul li:hover {
		background: #4b545f;
		background: linear-gradient(top, #4f5964 0%, #5f6975 40%);
		background: -moz-linear-gradient(top, #4f5964 0%, #5f6975 40%);
		background: -webkit-linear-gradient(top, #4f5964 0%,#5f6975 40%);
}

nav ul li:hover a {
		color: #fff;
}

nav ul li a {
	display: block;
  padding: 25px 40px;
	color: #757575;
  text-decoration: none;
}

nav ul ul {
	background: #5f6975;
  border-radius: 0px;
  padding: 0;
	position: absolute;
  top: 100%;
}