Black border around images

Hello! I have a wordpress blog template that’s doctored up just slightly with custom design.

BUT I would like one small change to happen on my blog — to get rid of the black border that surrounds all of my blog images. When the cursor goes over any given image, the border turns a dark gray color, which I would like to get rid of also (though that’s not a deal breaker for me as much as the default black border).

Anyone can offer me any help??

my blog url: https://themoveablefeasts.wordpress.com/

Thank you! x