My nav bar doesn’t span vertically to fit the parent div. Why?

http://acjdesigns.com

I’m using a child theme on wordpress and for some reason, the nav bar doesn’t span to fit the div “header”. I tried height: 100% for all the parts.

.main-nav {
    float: right;
    border: none;
    position: relative;
    margin: 0px auto;
    padding: 0px;
    clear: none;
    height: 100%;
}
.menu, .menu ul {
    text-decoration: none;
    text-shadow: 0px;
    margin: 0px auto;
    padding: 0px;
    clear: none;
    height: 100%;
}
.menu li a:link {
    border: none;
    color: #353535;
    background-color: white;
    text-transform: lowercase;
    font-family:'Open Sans', sans-serif;
    text-shadow: 0px 0px 0px;
    font-weight: normal;
    font-size: 15px;
    background-image: none;
}
.menu li a:visited {
    border: none;
    color: #353535;
    background-color: white;
    text-transform: lowercase;
    font-family:'Open Sans', sans-serif;
    text-shadow: 0px 0px 0px;
    font-weight: normal;
    font-size: 15px;
    background-image: none;
}
.menu li a:hover {
    border: none;
    color: DeepPink;
    text-transform: lowercase;
    background-color: white;
    font-family:'Open Sans', sans-serif;
    text-shadow: 0px 0px 0px;
    font-weight: normal;
    font-size: 15px;
    background-image: none;
}
.menu li a:active {
    border: none;
    color: DeepSkyBlue;
    text-transform: lowercase;
    background-color: white;
    font-family:'Open Sans', sans-serif;
    text-shadow: 0px 0px 0px;
    font-weight:normal;
    font-size: 15px;
    background-image: none;
}

As per request, the HTML:

<div id="header">       
<div id="logo">
    <a href="http://acjdesigns.com/"><img src="http://acjdesigns.com/wp-content/uploads/2014/01/cropped-copy-Logo-012.png" width="250" height="54" alt="ACJ Designs"/></a>
    </div><!-- end of #logo -->
    <div class="main-nav">
      <ul class="menu">
        <li class="current_page_item"><a href="http://acjdesigns.com/">Home</a></li>
        <li class="page_item page-item-34"><a href="http://acjdesigns.com/bio">bio</a></li>
        <li class="page_item page-item-39"><a href="http://acjdesigns.com/graphics">graphics</a></li>
        <li class="page_item page-item-101"><a href="http://acjdesigns.com/photography-2">photography</a></li>
        <li class="page_item page-item-41"><a href="http://acjdesigns.com/other-works">other works</a></li>
   </ul>
</div>
</div><!-- end of #header -->

I don’t have my header div set to a height, so maybe that’s the problem? Any help would be great. Thanks ahead of time!