#content img {
   display: block;
   margin-left: auto;
   margin-right: auto;
   margin-top: 100px;
}

#header {
   background-color: #000;
   height: 30px;
}

#header-navigation {
   float: right;
}

#header-navigation a {
   color: #FFF;
   text-decoration: none;
}

#header-navigation li ul li a {
   color: #000;
}

#header-navigation a:hover {
   text-decoration: underline;
}

/* Adapted from http://www.alistapart.com/articles/dropdowns/ */
#header-navigation ul {
  padding: 0;
  margin: 0;
  list-style: none;
}

#header-navigation li {
  float: left;
  position: relative;
  width: 10em;
}

#header-navigation li ul {
  display: none;
  position: absolute; 
  top: 1em;
  left: 0;
   border: 1px solid black;
   background-color: white;
}

#header-navigation li > ul {
   top: auto;
   left: auto;
}

#header-navigation li:hover ul { display: block; }