https://www.w3.org/TR/css-typed-om-1/#numericvalue-serialization > 4. Otherwise, if unit is "percentage", append "%" to s, then return s. If the `CSSUnitValue` object was created via [`CSS.percent(n)`](https://www.w3.org/TR/css-typed-om-1/#numeric-factory), the _unit_ value will be `"percent"`.
https://www.w3.org/TR/css-typed-om-1/#numericvalue-serialization
If the
CSSUnitValueobject was created viaCSS.percent(n), the unit value will be"percent".