Arched Shaped Images Resizing

Hello...I have noticed that when my webpage is open on a browser that is not fully sized to fit the screen, the images resize/deform in a strange way. It's especially noticeable on images that I have shaped as arches, but the rectangular picture I have at the top of my website gets squished in a weird way as well.  Is this normal for fluid engine sections? Do you have any recommendations as to what I can do to prevent this weird look? I do like the way the arches look at full screen but if I have to change them I suppose I can. You can view my homepage at the link below. Also, the arched image at the top of my homepage is a gif of rotating images if that makes any difference.

 https://www.thepemberleycreative.com/