Bootstrap -problemy z galerią zdjęć oraz z "navbar"

Cześć! Mam problem ze stroną internetową tworzoną za pomocą Boostrapa. Gdy chcę stworzyć galerię i powiększam zdjęcie, to górne menu nie znika, ale pozostaje wciąż aktywne (dosłownie znajduje się na powiększonym zdjęciu). Poniżej podaję fragment kodu z navbarem: 

<nav class="navbar navbar-default">
  <div class="container-fluid">
    <div class="navbar-header">
      <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#myNavbar">
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span> 
      </button>
        <a class="navbar-brand">
             <a href="index.html"><span class="glyphicon glyphicon-home bg-6"></a></span>
             <a href="#"></a>
                            <img src="fb2.png" style="width: 35px; height: 35px; left: 40px; margin-top: 8px" alt="Facebook">
                           
                                <div class="visible-lg-block">
                            <h5 class="center-block" style="position: absolute; top: 8px; left: 200px;"><strong>"#"</h5>
                                </div>
      
        
    </div>
    <div class="collapse navbar-collapse" id="myNavbar">
      <ul class="nav navbar-nav navbar-right">
        <li><a href="Index.html">O Poradni</a></li>
        <li><a href="Kadra.html">Kadra</a></li>
        <li><a href="Galeria.html">Galeria</a></li>
        <li><a href="Kontakt.php">Kontakt</a></li>
      </ul>
    </div>
  </div>
</nav>

oraz kod do początkowej galerii: 

<h2 style="text-align:center">Galeria:</h2>
        
        <!-- Trigger the Modal -->
<img id="myImg" src="#" alt="#" width="300" height="200">

<!-- The Modal -->
<div id="myModal" class="modal">

  <!-- The Close Button -->
  <span class="close" onclick="document.getElementById('myModal').style.display='none'">&times;</span>

  <!-- Modal Content (The Image) -->
  <img class="modal-content" id="img01">

  <!-- Modal Caption (Image Text) -->
  <div id="caption"></div>
</div>

<script>
        // Get the modal
var modal = document.getElementById('myModal');

// Get the image and insert it inside the modal - use its "alt" text as a caption
var img = document.getElementById('myImg');
var modalImg = document.getElementById("img01");
var captionText = document.getElementById("caption");
img.onclick = function(){
    modal.style.display = "block";
    modalImg.src = this.src;
    modalImg.alt = this.alt;
    captionText.innerHTML = this.alt;
}

// Get the <span> element that closes the modal
var span = document.getElementsByClassName("close")[0];

// When the user clicks on <span> (x), close the modal
span.onclick = function() { 
  modal.style.display = "none";
}
</script>

oraz CSS:

.features .glyphicon{
                font-size: 50px;
            }
            
            .navbar {
                margin-bottom: 0px;
                background-color:whitesmoke;
                z-index: 9999;
                border: 0px;
                font-size: 18px !important;
                line-height: 1.42857143 !important;
                letter-spacing: 2px;
                border-radius: 0;
                margin: 5px;
                
            }
            
            .navbar li a {
                color: white;
            }
            
            .navbar .navbar-brand {
             color: black !important;
             }
             .bg-6 {
                 position: absolute;
                 font-size: 35px;
                 left: 95px;
                 bottom: 4px;
                 top: 8px;
                 color:  black;
                 opacity: 0.8;
                 
             }
             #myImg {
    border-radius: 5px;
    cursor: pointer;
    transition: 0.3s;
}

#myImg:hover {opacity: 0.7;}

/* The Modal (background) */
.modal {
    display: none; /* Hidden by default */
    position: fixed; /* Stay in place */
    z-index: 1; /* Sit on top */
    padding-top: 100px; /* Location of the box */
    left: 0;
    top: 0;
    width: 100%; /* Full width */
    height: 100%; /* Full height */
    overflow: auto; /* Enable scroll if needed */
    background-color: rgb(0,0,0); /* Fallback color */
    background-color: rgba(0,0,0,0.9); /* Black w/ opacity */
}

/* Modal Content (Image) */
.modal-content {
    margin: auto;
    display: block;
    width: 80%;
    max-width: 700px;
}

/* Caption of Modal Image (Image Text) - Same Width as the Image */
#caption {
    margin: auto;
    display: block;
    width: 80%;
    max-width: 700px;
    text-align: center;
    color: #ccc;
    padding: 10px 0;
    height: 150px;
}

/* Add Animation - Zoom in the Modal */
.modal-content, #caption { 
    -webkit-animation-name: zoom;
    -webkit-animation-duration: 0.6s;
    animation-name: zoom;
    animation-duration: 0.6s;
}

@-webkit-keyframes zoom {
    from {-webkit-transform:scale(0)} 
    to {-webkit-transform:scale(1)}
}

@keyframes zoom {
    from {transform:scale(0)} 
    to {transform:scale(1)}
}

/* The Close Button */
.close {
    position: absolute;
    top: 15px;
    right: 35px;
    color: #f1f1f1;
    font-size: 40px;
    font-weight: bold;
    transition: 0.3s;
}

.close:hover,
.close:focus {
    color: #bbb;
    text-decoration: none;
    cursor: pointer;
}

/* 100% Image Width on Smaller Screens */
@media only screen and (max-width: 700px){
    .modal-content {
        width: 100%;
    }
}
            

Z góry dziękuję za pomoc!