.img-border { 
    border-radius: 5% 5% 5% 5% / 7% 7% 7% 7%
}
.theme-col:hover .theme-div {
    filter: brightness(0.5);
}
.theme-col:hover .theme-div-button { opacity:1 }

.theme-div-button {
    height: max-content;
    width: max-content;
    overflow: hidden;
    position: absolute;
    right: 40%;
    top: 38%;
    z-index: 10;
    opacity:0;
    transition:0.5s all;
}

.theme-col .fas {
    background: #adb5bd;
    border-radius: 50%;
    font-size: 15px;
    height: 30px;
    left: 7px;
    line-height: 30px;
    position: absolute;
    text-align: center;
    top: 6px;
    width: 30px;
    cursor: pointer;
}