rega measured 13 controls under the 24px minimum in the country map's legend at 390px: the tier tabs
at 22px tall, their info buttons at 18x22, and the row carets. The tabs take a 24px minimum height and
the info buttons a 24px square. The carets grow to 24x24 while a -5px margin returns the extra space,
so the tree's indentation (which shares the caret width) does not move. One library component, so
every map with this legend gets it.
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