Black Border on Image – CSS is clean

I have added a clickable image in my sidebar. An ugly black border surrounds the image. See here: https://thebuzzbuilder.com

CSS shows:
img.alignright {float:right; margin:0 0 1em 1em; border: none}
img.alignleft {float:left; margin:0 1em 1em 0; border: none;}
img.aligncenter {display: block; margin-left: auto; margin-right: auto; border: none;}
a img.alignright {float:right; margin:0 0 1em 1em; border: none;}
a img.alignleft {float:left; margin:0 1em 1em 0; border: none;}
a img.aligncenter {display: block; margin-left: auto; margin-right: auto; border: none;}

I have also searched for the word “border” in the CSS and it doesn’t appear anywhere else.

Does anyone have any ideas of how to get rid of this ugly black outline?