.ck-dropdown__panel.ck-dropdown__panel_sme.ck-dropdown__panel-visible {
    overflow: auto;
    max-height: 30em;
    max-width: 20em;
}

.ck-dropdown__panel.ck-dropdown__panel_se.ck-dropdown__panel-visible {
    overflow: auto;
    max-height: 30em;
    max-width: 20em;
}