1px black line appearing down right side of thumbnails (theme snaps) [closed]

For some reason, I think the image does not take all available space that it has, you can add a width: 100%; on the .post-thumbnail img. It solves the issue here.

Edit: You can see, by looking at the chrome dev tools (or firefox/IE) that the container does not have the save width as it children :

enter image description here
enter image description here