title: Adding a top navigation bar in a html page with a 100% high css element
body: <p>I am trying to add a navigation bar in my html template but it gets covered by the map which has height = 100%.
  This is my map style:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>#windyty {
    height: 100%;
    width: 100%;
    position: absolute;
    top: 0px;
    left: 0px;
  }
  
  ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    border: 1px solid #e7e7e7;
    background-color: #f3f3f3;
  }
  
  li {
    float: left;
  }
  
  li a {
    display: block;
    color: #666;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
  }
  
  li a:hover:not(.active) {
    background-color: #ddd;
  }
  
  li a.active {
    color: white;
    background-color: #4CAF50;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/leaflet/0.7.7/leaflet.js"&gt;&lt;/script&gt;
  &lt;link rel="stylesheet" href="resources/css/bootstrap-3.3.6.min.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/font-awesome-4.7.0.min.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/bootstrap-social-4.12.0.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/ie10-viewport-bug-workaround.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/bootstrap-datetimepicker-4.17.37.min.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/jquery.dataTables-1.10.12.min.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/buttons.dataTables-1.2.2.min.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/buttons.bootstrap-1.2.2.min.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/leaflet-0.7.7.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/leaflet.extra-markers.min.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/easy-button.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/leaflet-sidebar.min.css"&gt;
  &lt;link rel="stylesheet" href="resources/css/styles-min-20170519174922.css"&gt;
  
  &lt;link rel="stylesheet" type="text/css" href="http://cdn.leafletjs.com/leaflet/v0.7.7/leaflet.css" /&gt;
  &lt;link rel="stylesheet" type="text/css" href="http://cdnjs.cloudflare.com/ajax/libs/leaflet.markercluster/0.4.0/MarkerCluster.css" /&gt;
  &lt;link rel="stylesheet" type="text/css" href="http://cdnjs.cloudflare.com/ajax/libs/leaflet.markercluster/0.4.0/MarkerCluster.Default.css" /&gt;
  
  &lt;script type='text/javascript' src='http://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js'&gt;&lt;/script&gt;
  &lt;script type='text/javascript' src='http://cdn.leafletjs.com/leaflet/v0.7.7/leaflet.js'&gt;&lt;/script&gt;
  &lt;script type='text/javascript' src='http://cdnjs.cloudflare.com/ajax/libs/leaflet.markercluster/0.4.0/leaflet.markercluster.js'&gt;&lt;/script&gt;
  
  
  &lt;ul&gt;
    &lt;li&gt;&lt;a class="active" href="#home"&gt;Home&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;&lt;a href="#news"&gt;News&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;&lt;a href="#contact"&gt;Contact&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;&lt;a href="#about"&gt;About&lt;/a&gt;&lt;/li&gt;
  &lt;/ul&gt;
  
  &lt;div id="windyty"&gt;&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>ce that my navigation bar still exists but it's covered by the map. How can I do to add a navigation bar which is always visible? I am new to coding so sorry if this is trivial.
  Thanks</p>