This, though, is not universal: some display typefaces such as Cochin and Koch-Antiqua intended for publicity uses have low x-heights, to give them a more elegant, delicate appearance, a mannerism that was particularly common in the early twentieth century.
Medium x-heights are found on fonts intended for body text, allowing more balance and contrast between upper- and lowercase letters and a brighter page.
[4][5] High x-heights on display typefaces were particularly common in designs in the 1960s and '70s, when International Typeface Corporation released popular variations of older designs with boosted x-heights; notable examples of this trend include Avant Garde Gothic and ITC Garamond.
[6][7] More recently, some typefaces such as Mrs Eaves, Neutraface and Brandon Grotesque have been issued with distinctively low x-heights to try to create a more elegant appearance.
Thus, the exact ratio of ex to em can vary by font size within a browser if the determined values are rounded to the nearest whole unit.