7.1 - Box shadow on certain images doesn't work, it creates "edges" that weren't there before

Hi all. On my Books page I have 4 book covers that I want to have box shadow. When I enter the code below it causes the edges of the book image to be visible and it looks very bad. The only way I can get the box shadow to look right is with the SquareKicker plugin. That is sub optimal. How do I do this with code?

Thanks. 

Books page: https://activefengshui.com/feng-shui-books

#block-920e4c0018ece277fc48 {
  box-shadow: 1px 2px 10px 4px rgba(0,0,0,0.5);
}

Can you share link to Books Page?