- %: measurement relative to another value (typically enclosing)
- cm: centimeters.
- em: A relative measurement for the height of a font in em spaces. Because an em unit is equivalent to the size of a given font, if you assign a font to 12pt, each "em" unit would be 12pt; thus, 2em would be 24pt. The font-size unit em is a relative measure: one em is equal to the default font size on whatever screen the user is using. That makes it great for smartphone screens, since it doesn't try to tell the smartphone exactly how big to make a font
- ex: This value defines a measurement relative to a font's x-height. The x- height is determined by the height of the font's lowercase letter x.
- in: inches
- mm: millimeters.
- pc: picas. Defines a measurement in picas. A pica is equivalent to 12 points; thus, there are 6 picas per inch.
- pt: points. Defines a measurement in points. A point is defined as 1/72nd of an inch.
- px: pixels. Defines a measurement in screen pixels.