Hover menu

 
  #menu-box {background: silver; repeat-x 0 0;}
  #menu {width: 960px; margin: 0 auto;}

 #menu li {
  float: left;
   display: inline;
   list-style-type: none;
   text-align: center;
}

 #menu li a {
  text-decoration: none;
   color: white;
   float: left;
   display: inline;
   line-height: 35px;
   padding: 0 18px;
}

#menu ul ul {visibility: hidden;}
        
 #menu ul li:hover ul{visibility: visible;}

 #menu li a:hover, #menu li a.active {color: black;}

 /* Clearfix */
 .clearfix:after {
   display: block;
   clear: both;
   visibility: hidden;
   height: 0;
   font-size: 0;
   content: ' ';
 }

 .clearfix {min-height: 1px;}
 .clearfix {display: inline-block;}

 /* Backslash hack - nemel by to videt IE/Mac \*/
 .clearfix {display: block;}
 /* Konec hacku */

<div id="menu-box"> 
 <ul id="menu" class="clearfix">
   <li class="first"><a class="active" href="/">Úvod</a>
    <ul>
      <li><a href="#">aaaa</a></li>
    </ul>
    </li>
   <li><a href="#">Autoři</a></li>
   <li><a href="#">Články</a></li>
   <li><a href="#">Fotografie</a></li>
   <li><a href="#">Kontakt</a></li>
 </ul>
 </div>