.venntooltip {
    position: absolute;
    text-align: center;
    width: 128px;
    height: 22px;
    background: #333;
    color: #ddd;
    border: 0px;
    border-radius: 8px;
    opacity: 0;
}
.venn-area > .label {
    font-size: 1em;
}