I need some help troubleshooting. I want to use this gallery on webkit only devices, with a backup static photo collage for non-webkit devices. I got it working with minimal changes from this codeset, but Outlook 2010 will not display anything past the first image. What am I missing?

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Untitled Document</title>

<style>

html, body { background: #333; }

.slides {
padding: 0;
width: 609px;
height: 420px;
display: block;
margin: 0 auto;
position: relative;
}

.slides * {
user-select: none;
-ms-user-select: none;
-moz-user-select: none;
-khtml-user-select: none;
-webkit-user-select: none;
-webkit-touch-callout: none;
}

.slides input { display: none; }

.slide-container { display: block; }

.slide {
top: 0;
opacity: 0;
width: 609px;
height: 420px;
display: block;
position: absolute;

transform: scale(0);

transition: all .7s ease-in-out;
}

.slide img {
width: 100%;
height: 100%;
}

.nav label {
width: 200px;
height: 100%;
display: none;
position: absolute;

opacity: 0;
z-index: 9;
cursor: pointer;

transition: opacity .2s;

color: #FFF;
font-size: 156pt;
text-align: center;
line-height: 380px;
font-family: sans-serif;
background-color: rgba(255, 255, 255, .3);
text-shadow: 0px 0px 15px rgb(119, 119, 119);
}

.slide:hover + .nav label { opacity: 0.5; }

.nav label:hover { opacity: 1; }

.nav .next { right: 0; }

input:checked + .slide-container  .slide {
opacity: 1;

transform: scale(1);

transition: opacity 1s ease-in-out;
}

input:checked + .slide-container .nav label { display: block; }

.nav-dots {
width: 100%;
bottom: 9px;
height: 11px;
display: block;
position: absolute;
text-align: center;
}

.nav-dots .nav-dot {
top: -5px;
width: 11px;
height: 11px;
margin: 0 4px;
position: relative;
border-radius: 100%;
display: inline-block;
background-color: rgba(0, 0, 0, 0.6);
}

.nav-dots .nav-dot:hover {
cursor: pointer;
background-color: rgba(0, 0, 0, 0.8);
}

input#img-1:checked ~ .nav-dots label#img-dot-1,
input#img-2:checked ~ .nav-dots label#img-dot-2,
input#img-3:checked ~ .nav-dots label#img-dot-3,
input#img-4:checked ~ .nav-dots label#img-dot-4,
input#img-5:checked ~ .nav-dots label#img-dot-5,
input#img-6:checked ~ .nav-dots label#img-dot-6 {
background: rgba(0, 0, 0, 0.8);
}   
</style>

</head>

<body>

<ul class="slides">
<input type="radio" name="radio-btn" id="img-1" checked />
<li class="slide-container">
<div class="slide">
<img src="http://trn.trains.com/~/media/images/trackside/photos/2017/303/bridges.jpg" />
</div>
<div class="nav">
<label for="img-6" class="prev">&#x2039;</label>
<label for="img-2" class="next">&#x203a;</label>
</div>
</li>

<input type="radio" name="radio-btn" id="img-2" />
<li class="slide-container">
<div class="slide">
<img src="http://trn.trains.com/~/media/images/trackside/photos/2017/303/croteau.jpg" />
</div>
<div class="nav">
<label for="img-1" class="prev">&#x2039;</label>
<label for="img-3" class="next">&#x203a;</label>
</div>
</li>

<input type="radio" name="radio-btn" id="img-3" />
<li class="slide-container">
<div class="slide">
<img src="http://trn.trains.com/~/media/images/trackside/photos/2017/303/krug.jpg" />
</div>
<div class="nav">
<label for="img-2" class="prev">&#x2039;</label>
<label for="img-4" class="next">&#x203a;</label>
</div>
</li>

<input type="radio" name="radio-btn" id="img-4" />
<li class="slide-container">
<div class="slide">
<img src="http://trn.trains.com/~/media/images/trackside/photos/2017/303/mayes.jpg" />
</div>
<div class="nav">
<label for="img-3" class="prev">&#x2039;</label>
<label for="img-5" class="next">&#x203a;</label>
</div>
</li>

<input type="radio" name="radio-btn" id="img-5" />
<li class="slide-container">
<div class="slide">
<img src="http://trn.trains.com/~/media/images/trackside/photos/2017/303/medlin.jpg" />
</div>
<div class="nav">
<label for="img-4" class="prev">&#x2039;</label>
<label for="img-6" class="next">&#x203a;</label>
</div>
</li>

<input type="radio" name="radio-btn" id="img-6" />
<li class="slide-container">
<div class="slide">
<img src="http://trn.trains.com/~/media/images/trackside/photos/2017/303/rockwell.jpg" />
</div>
<div class="nav">
<label for="img-5" class="prev">&#x2039;</label>
<label for="img-1" class="next">&#x203a;</label>
</div>
</li>

<li class="nav-dots">
<label for="img-1" class="nav-dot" id="img-dot-1"></label>
<label for="img-2" class="nav-dot" id="img-dot-2"></label>
<label for="img-3" class="nav-dot" id="img-dot-3"></label>
<label for="img-4" class="nav-dot" id="img-dot-4"></label>
<label for="img-5" class="nav-dot" id="img-dot-5"></label>
<label for="img-6" class="nav-dot" id="img-dot-6"></label>
</li>
</ul>

</body>
</html>