Module:Chem2/styles.css

.template-chem2-su { /* {{pp-template}} */
	display: inline-block;
	font-size: 80%;
	line-height: 1;
	vertical-align: -0.35em;
}

.template-chem2-su > span {
	display: block;
}

.template-chem2-su > span:empty:before {
	content: "\200b"; /* unicode zero width space character means this always has height */
}