Module:Charmap/styles.css explained

/* */table.template-charmap tr:first-child table.template-charmap tr:first-child th[colspan] /* The most specific possible descendant selectors are used as any HTML might end up in the preview cell */table.template-charmap tr:first-child th[colspan] > div table.template-charmap tr:first-child th[colspan] > div > div

table.template-charmap tr:first-child th[colspan] > div > div > span:nth-child(2)

table.template-charmap .smallcaps-cm

table.template-charmap td:first-child

/* Condense the Numeric Character references as they can be wider than the page */table.template-charmap .template-charmap-numchr td:nth-child(n+2)