Template:Calendar/styles.css

.calendar-purple {
	color: var(--color-base, #202122);
	background-color: #ccf;
}

.calendar-lightpurple {
	color: var(--color-base, #202122);
	background-color: #d8e0ff;
}

html.skin-theme-clientpref-night .calendar-purple {
	background-color: #2a2a5c;
}

html.skin-theme-clientpref-night .calendar-lightpurple {
	background-color: #202040;
}

@media screen and (prefers-color-scheme: dark){
    html.skin-theme-clientpref-os .calendar-purple {
		background-color: #2a2a5c;
	}
	
	html.skin-theme-clientpref-night .calendar-lightpurple {
		background-color: #202040;
	}
}