How to Stop Horizontal Scrolling When Using CSS for Automatic Scrolling Gallery?

I have a gallery of automatic scrolling logos on my home page. I have it set up how I want it to look, but I can't figure out how to stop the horizontal scroll for overflow.

Here's the code I'm using:

#section[data-section-id="6653b666a7fe4f73efaaeaa6"] {
overflow-x: hidden
}

.gallery-grid-wrapper {
display:flex !important;
animation: slideshow 30s linear infinite
}

.gallery-grid-wrapper .gallery-grid-item {
 min-width: 25%;
 margin-right: 5%
}

@keyframes slideshow {
  0%    { left: 0; }
  100%  { left: -205% }
}

Any help is much appreciated! 

Ahh thank you!!