CSS font-size Property Definition and Usage:-
Using CSS the size of the font sets by the font-size property.

CSS Syntax for font-size is as follows,

font-size: medium | xx-small | x-small | small | large | x-large | xx-large | smaller | larger | length | initial | inherit;

Example:-

Set the font size for different elements,

div.a { font-size: 15px; }
div.b { font-size: large; }
div.c { font-size: 150%; }