Reply To: Image border and shadow

The code you have above does work but it only targets images on a gallery.
To include single images on a post you can try this code. Either add it on Frontier Options -> Custom CSS or on a child-theme’s style.css

img[class*="align"],
img[class*="wp-image-"],
img[class*="attachment-"] {
   border: 1px solid #000;
   padding: 0px;
   box-shadow: 3px 3px 8px #2e2e2e;
}