I just got the Answer by changing the index of the slideshow images to -1 instead of 0.
.slideshow li {
width: 100%;
height: 100%;
position: absolute;
top: 0px;
left: 0px;
background-size: cover;
background-position: 50% 50%;
opacity: 0;
z-index: -1;
-webkit-animation: imageAnimation 36s linear infinite 0s;
-moz-animation: imageAnimation 36s linear infinite 0s;
-o-animation: imageAnimation 36s linear infinite 0s;
-ms-animation: imageAnimation 36s linear infinite 0s;
animation: imageAnimation 36s linear infinite 0s;
}