Using CSS var function in GeoServer CSS styling

I wanted to check if I could use something like the CSS var() function with the GeoServer CSS plugin styles.
Something to look like:

    :root {
        --land-color: #f2efe9;
      }
    /* @title Land */
    [featurecla = 'Land'] {
        background-color: var(land-color);
      }

Except obviously for more than one variable.
I came across this question but could not get the only suggested solution there to work.
This is what I tried:

/* &env=land-color:#dd0000 */
/* @title Land */
[featurecla = 'Land'] {
fill: env('land-color');
stroke: #f2efe9;
}

EDIT

The result I want to get is setting a color (or any other style variable, like halo-radius or font-size) once and the use it by name in entire stylesheet, making it easier to edit it across the document.

I keep getting a default white polygon with black stroke when using this. The CSS validates properly but does nothing.