Length Measurement Units In CSS3

CSS uses various units of measurements for specifying size of the font, width and height of margins, and so on. These units measure the horizontal and vertical length of the content. CSS supports two types of length measurement units namely, relative and absolute.

 Ø Relative: Relative length specifies the length units related to other length property that are calculated in comparison to a current value.

Relative length	Description
Em	Specifies the font size (height) of a particular font. The em unit is relative to the value of the font-size property of the selector
Px	Specifies the size in pixels, which is relative to the screen of the device
Ex	Specifies the ‘x-height’ of a particular font. The ‘x-height’ value is approximately half the font size or the height of the lowercase letter ‘x’.