How to add borders to gallery thumbnails

Site URL: https://sdbrosconsulting.com

Hey, I was looking to add a border to the thumbnail of the active picture of a gallery for a client.

I did not found much online so I came up with this code but it only adds a border to the top of the active thumbnail.

When trying to add the border to the entire thumbnail (using border: instead of border-top:, the bottom border was not visible, neither when using border-bottom:).

I'm think it actually looks better with the border on top only but if anyone knows how to have the border all-over please share!  .

sqs-block .sqs-gallery-thumbnails .sqs-gallery-design-strip-slide {
    opacity:0.5;
} //Changes opacity of thumbnails not selected

.sqs-block .sqs-gallery-thumbnails .sqs-gallery-design-strip-slide.sqs-active-slide {
    opacity:1;
border-top: 1px solid #000; 
  ;
} //Changes opacity of selected/active thumbnail and sets a border on top of it

Can you share link to gallery on your site?