title: DIV won't show up over a DIV that's underneath it
body: <p>I can't figure out how to get a DIV to show up over a DIV that's underneath it.  In other words, my webpage has a head, with a DIV that floats left and a DIV that floats right.  Underneath that is a menu bar.  I don't have many menu items, so I want image in the DIV that floats right to partially overlap the menu bar.  I'm able to make it work with absolute positioning... but that not ideal.  I went ahead and changed the width of the menu bar, but that's more of a temporary fix to get what I want.  Thoughts?</p>
  
  <p>www.sacspartans.org</p>
  
  <pre><code>&lt;div id="page" class="hfeed site"&gt;
  &lt;header id="masthead" class="site-header" role="banner"&gt;
      &lt;div id="header-left"&gt;      
              &lt;hgroup&gt;
          &lt;h1 class="site-title"&gt;
              &lt;a href="&lt;?php echo esc_url( home_url( '/' ) ); ?&gt;"&gt;
              &lt;img src="http://sacspartans.org/wp-        
                               content/uploads/2013/05/banner.png" alt="SacSpartans" 
                               title="SacSpartans" border="0" /&gt;
              &lt;/a&gt;
          &lt;/h1&gt;
          &lt;h2 class="site-description"&gt;&lt;?php bloginfo( 'description' ); ?&gt; 
                      &lt;/h2&gt;
              &lt;/hgroup&gt;
      &lt;/div&gt;  
      &lt;div id="header-right"&gt; 
          &lt;img src="http://sacspartans.org/wp-
                      content/uploads/2013/05/california1.png" alt="MSU Alumni Club of 
                      the Sacramento Valley" title="MSU Alumni Club of the Sacramento  
                      Valley" border="0" /&gt;
      &lt;/div&gt;
      &lt;div id="navigation-bar"&gt;
      &lt;nav id="site-navigation" class="main-navigation" role="navigation"&gt;
          &lt;h3 class="menu-toggle"&gt;&lt;?php _e( 'Menu', 'twentytwelve' ); ?&gt;&lt;/h3&gt;
          &lt;a class="assistive-text" href="#content" title="&lt;?php esc_attr_e( 
                      'Skip to content', 'twentytwelve' ); ?&gt;"&gt;&lt;?php _e( 'Skip to 
                      content', 'twentytwelve' ); ?&gt;&lt;/a&gt;
          &lt;?php wp_nav_menu( array( 'theme_location' =&gt; 'primary', 
                      'menu_class' =&gt; 'nav-menu' ) ); ?&gt;
      &lt;/nav&gt;
      &lt;/div&gt;
  </code></pre>
  
  <p>And now CSS info.</p>
  
  <pre><code>/* Header */
  #header-left {
  float: left;
  }
  
  #header-right {
  float: right;
  margin-top: 0;
  }
  
  #navigation-bar {
  width: 575px;
  }
  </code></pre>