combining styles across layers

example.css

http://wri-01.cartodb.com/tiles/rivers/7/43/66.png?sql=select 1 as lid, the_geom_webmercator from rivers UNION select 2 as lid, the_geom_webmercator from country_attributes_live where iso = 'BRA' &map_key=&style=
@adm1_line_color:#FFF;
@adm1_line_glowColor:#000;
#rivers {
[lid=1] {
  [zoom<=6]{
    line-width:0;
  }
  [zoom>=8]{
    line-width:2;
  }
  line-color:#168;
  line-opacity:0.4;
}
[lid=2] {
    line-color: @adm1_line_color;
    [zoom<=4]{
        line-opacity: 1;
        line-width:0.5;
        line-dasharray:2,5;
    }
    [zoom<6]{
        line-opacity: 1;
        line-width:1;
        line-dasharray:4,5;
    }
    [zoom>=6]{
        line-opacity: 1;
        line-width:2;
    }
    polygon-opacity:1;
    polygon-fill: transparent;
    ::glow{
        line-color:@adm1_line_glowColor;
        line-opacity:0.1;
        line-width:4;
    }
}