How Remove Border on Image Hover Windows

[yanick]

A recent change in either Flare or CSS requirements is causing thumbnail popups (the image that appears when I hover over a thumbnail) to display a black border. This border appears in Chrome, IE, Edge, and Opera, but not in Firefox.

How do I remove this border? I've tried adding

.img, img
{
border: none;
}

to both my CSS and to Flares' Topic.css without success.

Here's an example. First the current state with the unwanted black border:

Current.png

Then, the desired state (sans-border):

Desired.png

Thank-you