Editing Template:Color/styles.css

/* {{pp-template}} */
/* [[phab:T360683]]: This stylesheet removes the function of this template in
 * dark mode
 */

@media screen {
    html.skin-theme-clientpref-night div:not(.notheme) > .tmp-color,
	html.skin-theme-clientpref-night p > .tmp-color,
	html.skin-theme-clientpref-night table:not(.notheme) .tmp-color {
	   color: inherit !important;
	}
}

@media screen and ( prefers-color-scheme: dark) {
    /* automatic mode */
    html.skin-theme-clientpref-os div:not(.notheme) > .tmp-color,
    html.skin-theme-clientpref-os p > .tmp-color,
    html.skin-theme-clientpref-os table:not(.notheme) .tmp-color {
      color: inherit !important;
    }
}