.tooltip {
    position: relative;
    display: inline-block;
    font-size: 16px;
}

.tooltip .tooltiptext {
    visibility: hidden;
    background-color: black;
    color: #fff;
    text-align: center;
    padding: 5px 0;
    border-radius: 6px;
    position: absolute;
    z-index: 1;
    width: 150px;
    top: 100%;
    left: 50%;
    margin-left: -75px;
    font-size: 12px;
}

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