.error-marker {
    width: 6px;
    height: 1.5em;
    background: #ec1e24;
    transition: all 100ms;
    -webkit-transition: all 100ms;
}

.error-marker:hover {
    background: #d68;
}

.error-marker::before {
    opacity: 0;
    pointer-events: none;
    content: attr(message);
    transition: all 100ms;
    -webkit-transition: all 100ms;
    width: 175px;
    font-size: 10px;
    padding: 5px;
    border: 1px solid #000;
    position: absolute;
    background: #fff;
    z-index: 999;
}

.error-marker:hover::before {
    opacity: 1;
    margin-left: 35px;
}