Overshoot
Round and pointed letters poke slightly past the baseline or height guides so they look equal to flat-sided letters.
See it
What it is
Overshoot is the small distance a round or pointed glyph extends past an alignment line. A flat H can stop exactly at the baseline and cap height, but an O drawn to those same limits looks slightly smaller. Type designers push the O a little above and below; lowercase o passes the baseline and x-height for the same reason, and the apex of A often passes the cap height.
Reach for overshoot when drawing a typeface, lettering a logo, or checking why apparently mismatched glyph bounds are actually correct. Icon systems apply the same correction: Material Design's keyline shapes put an 18dp square and a 20dp circle inside the same 24dp grid, because matching the numbers would make the circle look small. Judge it at the intended reading size: the right amount depends on the shape, weight, contrast, and rasterization, not on one universal percentage.
Gotcha: overshoot is optical compensation, not sloppy alignment. Forcing every outline onto the same mathematical guides makes round and pointed forms look short. At small pixel sizes, hinting and grid fitting may reduce or hide the overshoot, so a zoomed outline view is not proof of how the type will look in text.
Ask AI for it
Build an SVG overshoot specimen from the supplied font using fontTools 'TTFont' and 'BoundsPen'. Draw H, O, x, o, and A at 300px, overlay the baseline plus x-height and cap-height from the font's OS/2 metrics. If 'sxHeight' or 'sCapHeight' is absent, use the measured bounds of x or H and label that fallback. Label every glyph's top and bottom bounds in font units, color only the portions of O, o, and A that cross a guide, report each overshoot as a percentage of unitsPerEm, and add a second rendering at 16px for comparison with the rasterized result.