.thumbBox{
    position: relative;
    display: none;
}

.thumbDelBtn{
    position: absolute;
    font-size: 60vh;
    background: transparent;
    border: transparent;
    visibility: hidden;
    opacity: 0.3;
}

.thumbBox:hover .thumbDelBtn{
    visibility: visible;
}

.thumbBox:hover .thumbImg{
    opacity: 0.5;
}