1A unit for measuring the width of printed matter, equal to the height of the type size being used.
- From there, sizing descendant elements with ems (a relative unit of measurement) becomes much more logical: 1em is 10 px, 1.6em is 16 px, .9em is 9px, and so forth.
- Sterne was almost compulsively attentive to page layout and typography, going so far as to specify the length of each dash in printer's ems.
- It doesn't matter which unit you use - zero horseshoes is the same as zero pixels, ems, or percentages.
1.1A unit of measurement equal to twelve points.
- So, a font size of 1.25 ems will be displayed as 1.25 pixels.
- This reduced the text to an unreadable level when the CSS specified sizes in ems, but only reduced it slightly when specified as percentages.
late 18th century: the letter M represented as a word, since it is approximately this width.