Module:Cite/styles.css

.citation-icon {
    margin-right: 4px;
    opacity: 0.3;
}

.citation-icon img {
    margin-bottom: 2px;
    height: 11px;
    width: auto;
}

ol.references li:target .citation-icon {
    opacity: 0.5;
}

/* Dark mode */
html.skin-citizen-dark .citation-icon img {
    filter: invert(1);
}