Height stretching on some photos

I would like to retain the width 100% responsive in the container of the sidebar area, then the height to be set auto (as each photo will vary in height OR trim the photo to fit fixed height such as 200px. As you can see it stretches the height of the photos. https://redefineddesignsbyroz.com/wproz/

https://www.ads-software.com/plugins/weptile-image-slider-widget/