The font-size CSS property sets the size of the font. Changing the font size also updates the sizes of the font size-relative
|Applies to||all elements. It also applies to ::first-letter and ::first-line.|
Absolute-size keywords, based on the user's default font size (which is medium).
Relative-size keywords. The font will be larger or smaller relative to the parent element's font size, roughly by the ratio used to separate the absolute-size keywords above.
value. For most font-relative units (such as em and ex), the font size is relative to the parent element's font size.
For font-relative units that are root-based (such as rem), the font size is relative to the size of the font used by the (root) element.
value, relative to the parent element's font size.