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<!DOCTYPE html>
<html>
<title>W3.CSS</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="../lib/w3.css">
<body>

<h2 class="w3-center">Manual Slideshow</h2>

<div class="w3-content" style="max-width:800px;position:relative">

<img class="mySlides" src="img_fjords.jpg" style="width:100%">
<img class="mySlides" src="img_lights.jpg" style="width:100%">
<img class="mySlides" src="img_mountains.jpg" style="width:100%">
<img class="mySlides" src="img_forest.jpg" style="width:100%">

<a class="w3-btn-floating" style="position:absolute;top:45%;left:0" onclick="plusDivs(-1)">❮</a>
<a class="w3-btn-floating" style="position:absolute;top:45%;right:0" onclick="plusDivs(1)">❯</a>

</div>

<script>
var slideIndex = 1;
showDivs(slideIndex);

function plusDivs(n) {
  showDivs(slideIndex += n);
}

function showDivs(n) {
  var i;
  var x = document.getElementsByClassName("mySlides");
  if (n > x.length) {slideIndex = 1}    
  if (n < 1) {slideIndex = x.length} ;
  for (i = 0; i < x.length; i++) {
     x[i].style.display = "none";  
  }
  x[slideIndex-1].style.display = "block";  
}
</script>

</body>
</html>