Need help with my Horizontal Scrolling images

Hey everyone! I need some help with a Horizontal Scrolling images on my website which can be found here (specifically at the bottom of the home page). I followed this tutorial and adjusted it to the best of my ability. But for some reason, there's some lag at the end of the animation it just jumps back, when I'd like it to scroll cleanly. Here's the current version of the code: 

#page {
overflow-x:hidden
}
.gallery-grid-wrapper {
display:flex !important;
animation:slideshow 16s linear infinite
}
.gallery-grid-wrapper .gallery-grid-item {
 min-width: 5%;
 margin-right: 5%
}
@keyframes slideshow {
  0%    { left: 0; }
  100%  { left: -117%; }
}

If anyone has any idea on how to fix this, please let me know! And thanks for taking the time to read!