CSS tooltip

tooltip.css

/* ToolTip */

[aria-label].has-tooltip {
    position: relative;
}

[aria-label].has-tooltip::after {
    display: block;
    content: attr(aria-label);
    width: auto;

    position: absolute;
    bottom: 100%;
    left: 50%;
    padding: 0.5rem;
    pointer-events: none;

    font-size: 0.75rem;
    white-space: nowrap;
    line-height: 1;
    color: #fff;
    background-color: #000;
    border-radius: 0.25rem;

    opacity: 0;
    transform: translate(-50%, 0);
    transition: all 0.2s ease;
}

[aria-label].has-tooltip:hover::after {
    opacity: 1;
    transform: translate(-50%, -0.25rem);
}