Length

ch represents the width, or more precisely the advance measure, of the glyph "0" (zero, the Unicode character U+0030) in the element's font.

em represents the calculated font-size of the element. If used on the font-size property itself, it represents the inherited font-size of the element.

1 pt is 4/3 of a pixel.

Pixels

rem represents the font-size of the root element (typically ). When used within the root element font-size, it represents its initial value (a common browser default is 16px, but user-defined preferences may modify this).

1 vh is equal to 1% of the height of the viewport's initial containing block

1 vmax is equal to the larger of 1 vw and 1 vh

1 vmin is equal to the smaller of 1 vw and 1 vh

1 vw is equal to 1% of the width of the viewport's initial containing block

Wrap the provided expression in CSS calc() function.