CSS Style form elements ( :in-range and :out-of-range pseudo-classes )

These pseudo-classes only applies to elements that have (and can take) a range limitation. In the absence of such a limitation, the element can neither be "in-range" nor "out-of-range."

[dailydeveloper]

Note that <input type="range"> can never match :out-of-range because the user cannot input such a value, and if the initial value is outside the range, the browser immediately clamps it to the minimum or maximum (as appropriate) bound of the range.