Problem mit Slideshow

<script type="text/javascript">
    
var slideIndex = 1;
showSlides(slideIndex);

// Next/previous controls
function plusSlides(n) {
  showSlides(slideIndex += n);
}

// Thumbnail image controls
function currentSlide(n) {
  showSlides(slideIndex = n);
}

function showSlides(n) {
  var i;
  var slides = document.getElementsByClassName("mySlides");
  var dots = document.getElementsByClassName("dot");
  if (n > slides.length) {slideIndex = 1}
  if (n < 1) {slideIndex = slides.length}
  for (i = 0; i < slides.length; i++) {
      slides[i].style.display = "none";
  }
  


  for (i = 0; i < dots.length; i++) {
      dots[i].className = dots[i].className.replace(" active", "");
  }
  slides[slideIndex-1].style.display = "block";
  dots[slideIndex-1].className += " active";
} 


</script>

<!-- Slideshow container -->
<div class="slideshow-container">

  <!-- Full-width images with number and caption text -->
  <div class="mySlides fade">

    <img src="Bilder/leichtbauhalle-haltec-basic-01.jpg" style="width:100%">
    <img src="Bilder/Testimonial1.png" class="Slideshow-img-Testimonial">

    <div class="Zitate fade" style="height:350px;width: 450px;"><p>Mit HALTEC war schnell die passende Lösung für meine Lageranforderungen gefunden. Die zügige Montage und Lieferung war klasse. Jederzeit wieder. </p>
        <img src="Bilder/Anfuehrungszeichen.png" class="quote">
        </div>
  
  </div>

  <div class="mySlides fade">
    
    <img src="Bilder/leichtbauhalle-haltec-basic-02.jpg" style="width:100%">

  </div>

  <div class="mySlides fade">
   
    <img src="Bilder/leichtbauhalle-haltec-basic-03.jpg" style="width:100%">
 
  </div>

  <!-- Next and previous buttons -->
  <a class="prev" onclick="plusSlides(-1)">&#10094;</a>
  <a class="next" onclick="plusSlides(1)">&#10095;</a>
</div>

/* Slideshow container */
.slideshow-container {
  max-width: 1434px;
  position: relative;
  margin: auto;
  text-align: start;
  margin-top:2em;
  margin-bottom: 5em;
  display:block;
}

/* Hide the images by default */
.mySlides {
  display: none;
}

/* Next & previous buttons */
.prev, .next {
  cursor: pointer;
  position: absolute;
  top: 50%;
  width: auto;
  margin-top: -22px;
  padding: 16px;
  color: white;
  font-weight: bold;
  font-size: 18px;
  transition: 0.6s ease;
  border-radius: 0 3px 3px 0;
  user-select: none;
  background-color:black;
}

/* Position the "next button" to the right */
.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}

/* On hover, add a black background color with a little bit see-through */
.prev:hover, .next:hover {
  background-color: rgba(0,0,0,0.8);
}



/* Fading animation */
.fade {
  -webkit-animation-name: fade;
  -webkit-animation-duration: 1.5s;
  animation-name: fade;
  animation-duration: 1.5s;
}

@-webkit-keyframes fade {
  from {opacity: .4}
  to {opacity: 1}
}

@keyframes fade {
  from {opacity: .4}
  to {opacity: 1}
}

   
.mySlides div.Zitate {background-color: white;
    position: absolute;
    margin-top: -33em;
    margin-left: 12em;
    -webkit-box-shadow: inset 0px -1px 26px -5px rgba(0,0,0,0.77);
-moz-box-shadow: inset 0px -1px 26px -5px rgba(0,0,0,0.77);
box-shadow: inset 0px -1px 26px -5px rgba(0,0,0,0.77);
    }

.mySlides div.Zitate p {padding:80px;padding-top:120px;
    padding-right:47px;padding-left:120px;color:#0096dc;font-size: 17px;font-family: KievitOT Light,sans-serif;}

.mySlides img.Slideshow-img-Testimonial {
    display: none;
    position: absolute;
    z-index: 400;
    display: block;
    margin-top: -27.7em;
}

.mySlides img.quote {position: absolute;display: block;padding-left: 350px;
margin-top: -21em;}