Module:Charmap/styles.css

table.template-charmap tr:first-child {
	height: 50px; /* this is magic from StackOverflow to make the height below work */
}
table.template-charmap tr:first-child th[colspan] {
	height: 100%;
}
table.template-charmap tr:first-child th[colspan] > div {
	display: inline-flex;
	flex-direction: column;
	height: 100%;
	padding: 0 0.5em;
}

table.template-charmap tr:first-child th[colspan] > div > span:nth-child(2) {
	/* It is possible that unusual font sizes will be set, so padding is in px and
	   line-height is set to one, so that there is no font-size dependant padding. */
	margin: auto;
	padding: 10px 0;
	font-size: 150%;
	line-height: 1;
}

table.template-charmap .smallcaps-cm {
	font-size: 85%;
	font-variant: small-caps;
}