SpoilerAlert/modules/ext.spoileralert.css

.spoiler {
    background-color: black;
    color: black;
    transition: color 0.5s ease;
    cursor: pointer;
}

.spoiler.revealed {
    color: white;
}

.spoiler:after {
    content: " "
}

.spoiler:before {
    content: " "
}