Gecko chrome @supports function for strings and numbers

Question

in Gecko chrome there is -moz-bool-pref it Evaluates to true if the preference is enabled, false otherwise.

for example

@media (-moz-bool-pref: "removePopupBorder") {
 ...
}

if in the about:config i set removePopupBorder to true the code will run if i set removePopupBorder to false the code will not run

now if i have multiple valid values for removePopupBorder like auto , then , none every one of these can run different codes

how can i check what is removePopupBorder value

the -moz-bool-pref only works with boolean values true or false but how can i work with strings or numbers