35. Menú horizontal  3 niveles

<div id='cssmenu'>
  <ul>
     <li class='active'><a href='index.html'>Home</a></li>
     <li class='has-sub '><a href='#'>Products</a>
        <ul>
           <li class='has-sub '><a href='#'>Product 1</a>
              <ul>
                 <li><a href='#'>Sub Item</a></li>
                 <li><a href='#'>Sub Item</a></li>
              </ul>
           </li>
           <li class='has-sub '><a href='#'>Product 2</a>
              <ul>
                 <li><a href='#'>Sub Item</a></li>
                 <li><a href='#'>Sub Item</a></li>
              </ul>
           </li>
        </ul>
     </li>
     <li><a href='#'>About</a></li>
     <li><a href='#'>Contact</a></li>
  </ul>
</div>

CSS

#cssmenu {padding: 0; margin: 0; border: 0;}
#cssmenu ul, #cssmenu li {list-style: none; margin: 0; padding: 0;}
#cssmenu ul {position: relative; z-index: 597; }
#cssmenu ul li { float: left; min-height: 1px; vertical-align: middle;}
#cssmenu ul li.hover,
#cssmenu ul li:hover {position: relative; z-index: 599; cursor: default;}
#cssmenu ul ul {visibility: hidden; position: absolute; top: 100%; left: 0; z-index: 598; width: 100%;}
#cssmenu ul ul li {float: none;}
#cssmenu ul ul ul {top: 0; left: auto; right: -99.5%; }
#cssmenu ul li:hover > ul { visibility: visible;}
#cssmenu ul ul {bottom: 0; left: 0;}
#cssmenu ul ul {margin-top: 0; }
#cssmenu ul ul li {font-weight: normal;}
#cssmenu a { display: block; line-height: 1em; text-decoration: none; }
#cssmenu {
  background: #fff;
  border-radius: 5px;
  border-bottom: 4px solid #1b9bff;
  font-family: 'Oxygen Mono', Tahoma, Arial, sans-serif;
  font-size: 12px; 
}

  #cssmenu > ul { *display: inline-block; }

  #cssmenu:after, #cssmenu ul:after {
    content: '';
    display: block;
    clear: both; 
}
#cssmenu a {
    background: #C7E7FF;
    color: #000;
  border-radius: 20px;
    padding: 0 20px; 
}
#cssmenu ul { text-transform: uppercase; }

    #cssmenu ul ul {
      border-top: 4px solid #1b9bff;
      text-transform: none;
      min-width: 190px; 
}
      #cssmenu ul ul a {
        background: #1b9bff;
        color: #FFF;
  border-radius: 5px;
        border: 1px solid #0082e7;
        border-top: 0 none;
        line-height: 150%;
        padding: 16px 20px; 
}
      #cssmenu ul ul ul { border-top: 0 none; }
      #cssmenu ul ul li { position: relative }
#cssmenu > ul > li > a { line-height: 48px;  }

#cssmenu ul ul li:first-child > a { 
  border-top: 1px solid #0082e7; 
border-radius: 5px;}
        #cssmenu ul ul li:hover > a { 
  background: #35a6ff;
}

        #cssmenu ul ul li:last-child > a {
          border-radius: 0 0 3px 3px;
          box-shadow: 0 1px 0 #1b9bff; 
  border-radius: 20px;
}
        #cssmenu ul ul li:last-child:hover > a { border-radius: 10px 5px 10px 5px; }
        #cssmenu ul ul li.has-sub > a:after {
          content: '+';
          position: absolute;
          top: 50%;
          right: 15px;
          margin-top: -8px;
}