Thank you, so much for the solution.
I continued trying things before your reply, and found a "brute force" solution. Hopefully, there will be no problems down the road, in which case, I'll definitely implement your suggested solution. For now, I thought to just lower the opacity of the ".portfolio-item .portfolio-image", by letting the background color show through...
.portfolio-item .portfolio-image,
.portfolio-item .portfolio-image a,
.portfolio-item .portfolio-image img {
display: block;
border-radius: 6px;
width: 100%;
opacity: .9;
height: auto;
}
Then, added a ":hover" for the .portfolio-image (and it's "a" and "src" attributes) to go along with the .portfolio-overlay ":hover" ...
.portfolio-item:hover .portfolio-image a,
.portfolio-item:hover .portfolio-image src,
.portfolio-item:hover .portfolio-image ,
.portfolio-item:hover .portfolio-overlay,
.iportfolio:hover .portfolio-overlay { opacity: 1; }
It seems to be working fine for now.
Thanks again!