/* Tooltip container */
.atooltip {
    position: relative;
    display: inline-block;
    /*border-bottom: 1px dotted black; !* If you want dots under the hoverable text *!*/
}

/* Tooltip text */
.atooltip .tooltiptext {
    visibility: hidden;
    width: 120px;
    background-color: black;
    color: #fff;
    text-align: center;
    padding: 5px 0;
    border-radius: 6px;

    /* Position the tooltip text - see examples below! */
    position: absolute;
    z-index: 1;
}

/* Show the tooltip text when you mouse over the tooltip container */
.atooltip:hover .tooltiptext {
    visibility: visible;
}