var not allowed in media (declaration)

[willstdueswissen]

first question:

this:
@Custom-Media --smaller-media only screen and (max-width: var(--smaller-max-width));

compiles to:
@media only screen and (max-width: var(--smaller-max-width)) {

also this:
@media only screen and (max-width: var(--smaller-max-width)) {

compiles to nothing (error: ARNING: undefined CSS custom media alias "--smaller-max-width")

why?

and second, is the mainter avaible?
Or is the project not longer maintained?