.img-black-blck, .img-black-blck img { 
padding: 0; margin: 0; 
-moz-border-radius: 15px; border-radius: 15px; 
}
 
.img-black-blck { margin: 25px auto; position: relative; text-align: center; }
.img-black-blck img { border: 2px solid #000; position: relative; z-index: 2; }

.img-black-blck:after {
    position: absolute;
    top: -5%;
    left: -5%;
    width: 81%;
    height: 20%;
    background: #000;
    border: 2px #000 solid;
    content: '';
    z-index: 1;
    -moz-border-radius: 15px;
    border-radius: 15px;
    margin: 0 0 0 0;
}

@media screen and (max-width: 1000px) { 
.img-black-blck { max-width: 80%; width: fit-content; }
}