CSS3-Slider mit der Pseudoclasse :checked

HTML

<div id="gallery">
 <div id="fullsize">
  <input type="radio" id="box1" name="nav"/>   
  <input type="radio" id="box2" name="nav"/>   
  <input type="radio" id="box3" name="nav"/>  
  <input type="radio" id="box4" name="nav"/>   
  <input type="radio" id="box5" name="nav"/>   
  <input type="radio" id="box6" name="nav"/>  
  <input type="radio" id="box7" name="nav"/>   
  <input type="radio" id="box8" name="nav"/>   
  <input type="radio" id="box9" name="nav"/>         
<div class="weg" id="pic1">
<img src="http://goo.gl/k6BhI" alt="pic1" /></div>
<div class="weg" id="pic2">
<img src="http://goo.gl/c0zLf" alt="pic2" /></div>
<div class="weg" id="pic3">
<img src="http://goo.gl/zfcd8" alt="pic3" /></div>
<div class="weg" id="pic4">
<img src="http://goo.gl/zLmJs" alt="pic4" /></div>
<div class="weg" id="pic5">
<img src="http://goo.gl/dSwXF" alt="pic5" /></div>
<div class="weg" id="pic6">
<img src="http://goo.gl/1fzMW" alt="pic6" /></div>
<div class="weg" id="pic7">
<img src="http://goo.gl/bsYCV" alt="pic7" /></div>
<div class="weg" id="pic8">
<img src="http://goo.gl/ch8ag" alt="pic8" /></div>
<div class="weg" id="pic9">
<img src="http://goo.gl/A19e3" alt="pic9" /></div>
 </div>
 <ul id="thumbnails">
  <li><label for="box1"><img src="http://goo.gl/1JGFl" /></label></li>
<li><label for="box2"><img src="http://goo.gl/khWLa" /></label></li>
<li><label for="box3"><img src="http://goo.gl/lNqSw" /></label></li>
<li><label for="box4"><img src="http://goo.gl/hBzbX" /></label></li>
<li><label for="box5"><img src="http://goo.gl/0ZJME" /></label></li>
<li><label for="box6"><img src="http://goo.gl/BcNqi" /></label></li>
<li><label for="box7"><img src="http://goo.gl/M4zP3" /></label></li>
<li><label for="box8"><img src="http://goo.gl/iQ58n" /></label></li>
<li><label for="box9"><img src="http://goo.gl/52dtm" /></label></li>
 </ul>
</div>

CSS

input {
    float: left;
    display: none;
}
#gallery {
    width: 600px;
    height: 780px;
    margin: 20px auto;
    position: relative;
    overflow: hidden;
    background: #111;
    border-radius: 10px;
    box-shadow: 0 0 10px rgba(0,0,0,0.5);
}
#fullsize {
    width: 7000px;
    height: 680px;
    position: relative;
}
#fullsize div {
    width: 700px;
    height: 680px;
    float: left;
}
#fullsize div img {
    display: block;
    border: 1px solid #ddd;
    margin: 0px auto;
}
ul#thumbnails {
    position: relative;
    padding: 0 0 0 70px;
    margin: 0 auto;
    list-style: none;
    left: 40px;
}
ul#thumbnails li { float: left }
ul#thumbnails li {
    height: auto;
    width: 50px;
    padding: 3px;
    display: block;
    text-decoration: none;
    background: #111;
}
ul#thumbnails li img {
    width: auto;
    height: auto;
    border: 0;
    padding: 0;
}
ul#thumbnails li:hover { opacity: 0.5 }
#pic1,
#pic2,
#pic3,
#pic4,
#pic5,
#pic6,
#pic7,
#pic8,
#pic9 {
    -moz-transition: 1s;
    -ms-transition: 1s;
    -o-transition: 1s;
    -webkit-transition: 1s;
    transition: 1s;
}
#pic1 {
    position: relative;
    top: 20px;
    left: 0px;
}
#pic2 {
    position: relative;
    top: 20px;
    left: 700px;
}
#pic3 {
    position: relative;
    top: 20px;
    left: 1400px;
}
#pic4 {
    position: relative;
    top: 20px;
    left: 2100px;
}
#pic5 {
    position: relative;
    top: 20px;
    left: 2800px;
}
#pic6 {
    position: relative;
    top: 20px;
    left: 3500px;
}
#pic7 {
    position: relative;
    top: 20px;
    left: 4200px;
}
#pic8 {
    position: relative;
    top: 20px;
    left: 4900px;
}
#pic9 {
    position: relative;
    top: 20px;
    left: 5600px;
}
#box1:checked ~ div { margin-left: 0px }
#box2:checked ~ div { margin-left: -700px }
#box3:checked ~ div { margin-left: -1400px }
#box4:checked ~ div { margin-left: -2100px }
#box5:checked ~ div { margin-left: -2800px }
#box6:checked ~ div { margin-left: -3500px }
#box7:checked ~ div {...