The CSS property font is a shorthand for font-style, font-variant, font-weight, font-strech,font-size, line-height, fant-family

Syntax

font:
    font-style
    font-variant
    font-weight
    font-size/line-height
    font-family

See the Pen
font-shorthand by majadc (@majadc)
on CodePen.

Mandatory values:

Without these values entire line of code will be null.

• font-size
• font-family

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

font-family: font family name | initial | inherit

Optional values:

Omitting these values doesn’t make mistake.

• font-style
• font-variant
• font-weight

If omitted one of values the code is valid. Omitted value doesn’t have value of its parent value.

font-style: normal | italic | oblique | initial | inherit

font-variant: normal | small-caps | initial | inherit

font-weight: normal | bold | bolder | lighter |
    100, 200, .. 400 (normal), 500,..900 |
    initial | inherit

Resources

MDN