magnacarto -mml roads.mml -builder mapserver -ms-no-map-block > layers.map

layer.map

LAYER
  NAME roads-outline
  MAXSCALEDENOM 200000
  STATUS ON
  TYPE LINE
  DATA "hamburg_germany/hamburg_germany_osm_roads"
  PROJECTION
    "init=epsg:4326"
  END
  CLASS
    # Zoom{>=14}
    MAXSCALEDENOM 50000
    EXPRESSION ('[type]' = "secondary")
    STYLE
      WIDTH 4
      COLOR "#000000"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
  CLASS
    # Zoom{>=14}
    MAXSCALEDENOM 50000
    EXPRESSION ('[type]' = "primary")
    STYLE
      WIDTH 4
      COLOR "#000000"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
  CLASS
    # Zoom{>=14}
    MAXSCALEDENOM 50000
    EXPRESSION ('[type]' = "trunk")
    STYLE
      WIDTH 4
      COLOR "#000000"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
  CLASS
    # Zoom{>=14}
    MAXSCALEDENOM 50000
    EXPRESSION ('[type]' = "motorway")
    STYLE
      WIDTH 4
      COLOR "#000000"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
  CLASS
    # Zoom{>=12}
    MAXSCALEDENOM 200000
    EXPRESSION ('[type]' = "motorway")
    STYLE
      WIDTH 4
      COLOR "#000000"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
END
LAYER
  NAME roads-inline
  MAXSCALEDENOM 200000
  STATUS ON
  TYPE LINE
  DATA "hamburg_germany/hamburg_germany_osm_roads"
  PROJECTION
    "init=epsg:4326"
  END
  CLASS
    # Zoom{>=14}
    MAXSCALEDENOM 50000
    EXPRESSION ('[type]' = "secondary")
    STYLE
      WIDTH 3
      COLOR "#ffffff"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
  CLASS
    # Zoom{>=14}
    MAXSCALEDENOM 50000
    EXPRESSION ('[type]' = "primary")
    STYLE
      WIDTH 3
      COLOR "#f5f5dc"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
  CLASS
    # Zoom{>=14}
    MAXSCALEDENOM 50000
    EXPRESSION ('[type]' = "trunk")
    STYLE
      WIDTH 3
      COLOR "#ffff00"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
  CLASS
    # Zoom{>=14}
    MAXSCALEDENOM 50000
    EXPRESSION ('[type]' = "motorway")
    STYLE
      WIDTH 3
      COLOR "#ff0000"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
  CLASS
    # Zoom{>=12}
    MAXSCALEDENOM 200000
    EXPRESSION ('[type]' = "motorway")
    STYLE
      WIDTH 3
      COLOR "#ff0000"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
  CLASS
    # Zoom{>=14}
    MAXSCALEDENOM 50000
    STYLE
      WIDTH 0.5
      COLOR "#0000007f"
      LINECAP BUTT
      LINEJOIN MITER
    END
  END
END

roads.mss

@motorway_width: 3;
@trunk_width: 3;
@primary_width: 3;
@outline_width: 1;

#roads::outline[zoom>=12] {
    line-color: black;
}

#roads::inline[zoom>=12] {
    line-color: rgba(0, 0, 0, 0.5);
    [type='motorway'] { line-color: red; }
    [type='trunk'] { line-color: yellow; }
    [type='primary'] { line-color: beige; }
    [type='secondary'] { line-color: white; }
}

#roads::outline[zoom>=12] {
    [type='motorway'] { line-width: @motorway_width + @outline_width; }
}

#roads::inline[zoom>=12] {
    [type='motorway'] { line-width: @motorway_width; }
}

#roads::outline[zoom>=14] {
    [type='motorway'] { line-width: @motorway_width + @outline_width; }
    [type='trunk'] { line-width: @trunk_width + @outline_width; }
    [type='primary'],
    [type='secondary'] { line-width: @primary_width + @outline_width; }
}

#roads::inline[zoom>=14] {
    line-width: 0.5;
    [type='motorway'] { line-width: @motorway_width; }
    [type='trunk'] { line-width: @trunk_width; }
    [type='primary'],
    [type='secondary'] { line-width: @primary_width; }
}