Units in CSS

A unit of relative length:

The relative length is measured by the relationship to other things. A total of 3 relative length units: em,ex,px.

1 "em" is defined as the value of a font-size of a given font, for example, a font-size of one element is 14 pixels, and for that element, 1em is equal to 14 pixels.

Ex refers to the height of the small write x in the font used. If two paragraph text sizes are 24 points, but different fonts are used, their ex values are also different. In the actual problem, take the value of EM, and then take half of the value of ex.

PX is a pixel, which may be more appropriate for the border and positioning of an element than for pixels. If the margin uses EM, it may cause the design to widen or shrink as the text size changes.

Units in CSS