.tooltip {
    position: relative;
    display: inline-block;
    opacity: 1;
    z-index: 0;
}

.tooltip .tooltiptext {
    visibility: hidden;
    width: 120px;
    background-color: buttonface;
    color: black;
    text-align: center;
    border-radius: 6px;
    position: absolute;
    z-index: 1;
    top: 100%;
    margin-left: -30px;
}

.tooltip:hover .tooltiptext {
    visibility: visible;
}