HTML div not visible on server but visible on local machine

I have a column on the left side of my website that is called "sidebar". Within the sidebar, I have a div "nav" for the navigation and "adbox" which goes under the navigation to display an image of a map.

#sidebar {
  position: relative;
  float: left;
  text-align: center;
  width: 20%;
  padding: 0;
  border: 0;
  z-index: 1;
}

#navigation {
  width: 100%;
  background-color: transparent;
  padding: 0;
  margin: 0;
  border: 1px black dashed;
  text-align: center;
}

#navigation ul {
  list-style-type: none;
  width: 100%;
  display: block;
  margin: 0;
  padding: 0;
  text-align: center;
}

#navigation li {
  display: block;
  margin: 5px;
}

#navigation a {
  font-weight: bold;
  text-decoration: none;
  color: black;
  display: block;
  padding: 5px;
  border: 0px;
}

#navigation a:hover {
  font-weight: bold;
  text-decoration: none;
  color: white;
  background-color: maroon;
  border-radius: 15px;
  -webkit-border-radius: 15px;
  -moz-border-radius: 15px;
}

#adbox {
  width: 100%;
  margin: 40px auto 30px auto;
  padding: 0;
  text-align: center;
  float: left;
  display: block;
}
<div id="sidebar">
  <div id="navigation">
    <ul>
      <li><a href="index.html">Home</a></li>
      <li><a href="news.html">Important News</a></li>
      <li><a href="society.html">Society</a></li>
      <li><a href="photos.html">Photo Gallery</a></li>
      <li><a href="directions.html">Directions</a></li>
      <li><a href="donations.html">Donations</a></li>
      <li><a href="links.html">Links</a></li>
      <li><a href="contact.html">Contacts</a></li>
    </ul>
  </div>
  <div id="adbox">
    <a href="map.html"><img src="http://placehold.it/100x100" alt="" style="width:90%"></a>
    <a href="map.html">map</a>
  </div>
</div>

My issue is that the adbox seems to work fine on all of my browsers on my local machine. However when it is uploaded to the server, the adbox map does not work properly on chrome. It appears quickly for one second and then disappears. Why does it do this if it works fine on other browsers and works fine on my local machine?