Gallery Page - Slideshow Height

I've created a Gallery Page and added a Slideshow but on desktop the images get stretched and cause you have to scroll down to see the full image. I want to limit the height to 500px so the image is small and doesn't require desktop users to scroll. On mobile is looks fine. 

What CSS can I use to do this?

Here's a test page I've been playing with: https://www.aprilrainsphotography.com/test

Just wanted to bump this. 🙂

I've made some progress by using:

.collection-type-gallery.view-list .sqs-gallery-design-stacked-slide  {
  max-height: 500px !important;
}

However, now I have a large white space below the images.