inset – CSS: Cascading Style Sheets | MDN

as each of the properties of the shorthand:

  • top: if specified as a length, the corresponding absolute length; if specified as a percentage, the specified value; otherwise, auto
  • bottom: if specified as a length, the corresponding absolute length; if specified as a percentage, the specified value; otherwise, auto
  • left: if specified as a length, the corresponding absolute length; if specified as a percentage, the specified value; otherwise, auto
  • right: if specified as a length, the corresponding absolute length; if specified as a percentage, the specified value; otherwise, auto