http://ruseller.com/lessons/les2031/images/04-dropdown-menu-navigation.jpg
HTML

Код:
<header>
	<nav role="navigation">
    <ul>
    	<li>
        <a href="/">
        	<div>
            Home
            <span>there's no place like it</span>
        	</div>
        </a>
    	</li>
    	<li>
        <a href="/blog">
        	<div>
            Blog
            <span>my thoughts rock</span>
        	</div>
        </a><div>
        	<ul>
            <li><a href="#">Me</a></li>
            <li><a href="#">Gaming</a></li>
            <li><a href="#">Sport</a></li>
            <li><a href="#">Web Design</a></li>
            <li><a href="#">Web Development</a></li>
        	</ul>
        </div>
    	</li>
    	<li>
        <a href="/contact">
        	<div>
            Contact
            <span>drop me a line</span>
        	</div>
        </a>
    	</li>
    	<li>
        <a href="/forum">
        	<div>
            Forum
            <span>chat with others</span>
        	</div>
        </a>
    	</li>
    </ul>
	</nav>
</header>

CSS

Код:
* {margin: 0;padding: 0;outline: none;-webkit-box-sizing: border-box;-moz-box-sizing: border-box;box-sizing: border-box;}
*:after, *:before { -webkit-box-sizing: border-box;-moz-box-sizing: border-box;box-sizing: border-box;}
article,aside,details,figcaption,figure,footer,header,hgroup,nav,section {  display: block;}
html {font-size: 100%;height: auto !important;height: 100%;-webkit-text-size-adjust: 100%;-ms-text-size-adjust: 100%;}
.clear {display: block;	}
.clear::after {clear: both;content: ".";display: block;height: 1px;visibility: hidden;}
	
/*GENERIC STYLES*/
body { background: #f2f2f2;color: #222;-webkit-font-smoothing: antialiased;font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;font-size: 1.05em;font-weight: 400;height: auto !important;height: 100%;line-height: 1.6rem;min-height: 100%;}
/*NAV*/
	header {
    background: linear-gradient(to left,rgba(54,194,182,0.96) 0,rgba(62,188,207,0.96) 100%);
    border-bottom: 1px solid rgba(0,0,0,.1);
    box-shadow: 0 1px 1px 0 rgba(0,0,0,.1);
    display: block;
    position: fixed;
    width: 100%;
    z-index: 1000;
	}
	
	header > nav > ul {
    display: flex;
    flex-wrap: wrap;
    justify-content: flex-start;
    list-style: none;
    margin: 0;
    padding: 0;
	}
	
    header > nav > ul > li {
    	flex: 0 1 auto;
    	margin: 0;
    	padding: 0;
    	position: relative;
    	transition: all linear 0.1s;	
    }
    
    	header > nav > ul > li:hover {
        background: rgba(58,162,173,1);
    	}
    	
    	header > nav > ul > li a + div {
        background: linear-gradient(to bottom,rgba(58,162,173,1) 0,rgba(62,188,207,0.96) 100%);;
        border-radius: 0 0 2px 2px;
        box-shadow: 0 3px 1px rgba(0,0,0,.05);
        display: none;
        font-size: 1rem;
        position: absolute;
        width: 195px;
    	}
    	
        header > nav > ul > li:hover a + div {
        	display: block;
        }
        
        header > nav > ul > li a + div > ul {
        	list-style-type: none;	
        }
        
        	header > nav > ul > li a + div > ul > li {
            margin: 0;
            padding: 0;
        	}
        	
            header > nav > ul > li a + div > ul > li > a {
            	color: rgba(255,255,255,.9);
            	display: block;	
            	font-size: .75rem;
            	letter-spacing: 1.5px;
            	padding: .25rem 1.5rem;
            	text-decoration: none;
            	text-transform: uppercase;
            }
            
            	header > nav > ul > li a + div > ul > li:hover > a {
                background-color: rgba(0,0,0,.15);	
            	}
	
    	header > nav > ul > li > a {
        align-items: flex-start;
        color: #fff;
        display: flex;
        font-size: 1.55rem;
        font-weight: 200;
        letter-spacing: 1px;
        max-width: 130px;
        padding: 1rem 1.5rem;
        text-decoration: none;
        text-shadow: 0 1px 1px rgba(0,0,0,.1);
        transition: all linear 0.1s;
    	}
    	
        header > nav > ul > li > a > div > span {
        	color: rgba(255,255,255,.75);
        	display: block;
        	font-family: Georgia, "Times New Roman", Times, serif;
        	font-size: .7rem;	
        	font-style: italic;
        	line-height: 1rem;
        	max-width: 260px;
        }

@media (min-width: 990px) {
  header > nav > ul > li > a {
    max-width: 500px;
    font-size: 1.7rem;
	line-height: 2rem;
  }
  
  header > nav > ul > li > a > div > span {
	  margin: 4px 0 0;  
  }
}