MSS files for france house price map

france_borders.mss

/* ---- PALETTE ---- */

@city: #000;
@department: #eeeeee;
@region: #eeeeee;
@outline: #000;

/* ---- ZONE BORDERS ---- */

#adminzones::city_border[is_city=true]{
  line-width: 0;
  [zoom=9]{
    line-width: 0.05;
    line-color: @city;
    line-join: round;
    line-cap: round;
  }
  [zoom=10]{
    line-width: 0.2;
    line-color: @city;
    line-join: round;
    line-cap: round;
  }
  [zoom=11]{
    line-width: 0.3;
    line-color: @city;
    line-join: round;
    line-cap: round;
  }
}

#adminzones::department[is_department=true]{
  line-color: @department;
  line-join: round;
  line-cap: round;
  [zoom<7]{
    line-width: 0;
  }
  [zoom=7]{
    line-width: 1.5;
  }
  [zoom=8]{
    line-width: 2;
  }
  [zoom=9]{
    line-width: 3;
  }
  [zoom>9]{
    line-width: 4;
  }
}

#adminzones::region[is_region=true]{
  line-color: @region;
  line-join: round;
  line-cap: round;
  line-opacity:1;
  [zoom<7]{
    line-width: 1.5;
  }
  [zoom=7]{
    line-width: 3;
  }
  [zoom=8]{
    line-width: 4;
  } 
  [zoom=9]{
    line-width: 5;
  }
  [zoom=10]{
    line-width: 6;
  } 
}

#adminzones::country[is_country=true]{
  line-color: @department;
  line-join: round;
  line-cap: round;
  line-opacity:1;
  [zoom<7]{
    line-width: 2;
  }
  [zoom=7]{
    line-width: 3;
  }
  [zoom=8]{
    line-width: 4;
  }
  [zoom=9]{
    line-width: 5;
  }
  [zoom=10]{
    line-width: 6.5;
  }
  [zoom=11]{
    line-width: 10;
  }
}

/* ---- ZONE GRIDS FOR INTERACTION---- */

#adminzones::region_grid[is_department=true][zoom<7]{
  polygon-opacity: 0;
}

#adminzones::department_grid[is_department=true][zoom>6][zoom<10]{
  polygon-opacity: 0;
}

#adminzones::city_grid[is_city=true][zoom>9]{
  polygon-opacity: 0;
}

#adminzones::city_arr_grid[is_city_arr=true][zoom>9]{
  polygon-opacity: 0;
}

france_quantile_scale.mss

#adminzones::city[is_city=true][zoom>3]{
  polygon-opacity:0.8;
  line-opacity:0.2;
  line-width:0;
  [average_price_m2>0][average_price_m2<=761.275476828] { polygon-fill: #006837; line-color: #006837; line-width:1;  }
  [average_price_m2>761.275476828][average_price_m2<=1087.00614225] { polygon-fill: #1A9850; line-color: #1A9850; line-width:1;  }
  [average_price_m2>1087.00614225][average_price_m2<=1222.5984164] { polygon-fill: #66BD63; line-color: #66BD63; line-width:1;  }
  [average_price_m2>1222.5984164][average_price_m2<=1321.75374035] { polygon-fill: #A6D96A; line-color: #A6D96A; line-width:1;  }
  [average_price_m2>1321.75374035][average_price_m2<=1423.24897988] { polygon-fill: #D9EF8B; line-color: #D9EF8B; line-width:1;  }
  [average_price_m2>1423.24897988][average_price_m2<=1526.60500049] { polygon-fill: #FFFFBF; line-color: #FFFFBF; line-width:1;  }
  [average_price_m2>1526.60500049][average_price_m2<=1663.24815052] { polygon-fill: #FEE08B; line-color: #FEE08B; line-width:1;  }
  [average_price_m2>1663.24815052][average_price_m2<=1820.03985823] { polygon-fill: #FDAE61; line-color: #FDAE61; line-width:1;  }
  [average_price_m2>1820.03985823][average_price_m2<=2074.93451751] { polygon-fill: #F46D43; line-color: #F46D43; line-width:1;  }
  [average_price_m2>2074.93451751][average_price_m2<=3040.07930604] { polygon-fill: #D73027; line-color: #D73027; line-width:1;  }
  [average_price_m2>3040.07930604][average_price_m2<=50000] { polygon-fill: #A50026; line-color: #A50026; line-width:1;  }}
}

labels.mss

@font_reg: "Ubuntu Regular","Arial Regular","DejaVu Sans Book";

/* ---- MAIN CITIES ---- */

#stats::a_city[is_city=true][population>150000] {
  [zoom>5]{
    text-face-name:@font_reg;
    text-name:"[name]";
    text-fill:#444;
    text-halo-fill:rgba(255,255,255,0.8);
    text-halo-radius:1.5;
    text-transform:uppercase;
    [zoom>5]{
      text-size:10;
      text-wrap-width: 40;
    }
    [zoom=7]{
      text-size:11;
      text-wrap-width: 40;
    }
    [zoom=8]{
      text-size:12;
      text-wrap-width: 40;
    }
    [zoom=9]{
      text-size:13;
      text-wrap-width: 40;
    }
    [zoom>9]{
      text-size:14;
      text-wrap-width: 40;
    }
  }
}

#stats::b_city[is_city=true][population<150000][population>100000]{
  [zoom>7]{
    text-face-name:@font_reg;
    text-name:"[name]";
    text-fill:#444;
    text-halo-fill:rgba(255,255,255,0.8);
    text-halo-radius:1.5;
    text-transform:uppercase;
    [zoom>7]{
      text-size:10;
      text-wrap-width: 10;
    }
    [zoom=9]{
      text-size:11;
      text-wrap-width: 10;
    }
    [zoom>9]{
      text-size:12;
      text-wrap-width: 40;
    }
  }
}

#stats::c_city[is_city=true][population>30000][population<120000] {
  [zoom>9]{
    text-face-name:@font_reg;
    text-name:"[name]";
    text-fill:#444;
    text-halo-fill:rgba(255,255,255,0.8);
    text-halo-radius:1.5;
    text-transform:uppercase;
    [zoom=10]{
      text-size:9;
      text-wrap-width: 10;
    }
    [zoom=11]{
      text-size:10;
      text-wrap-width: 10;
    }
  }
}

I noticed in the france_quantile_scale.mss you are setting the line color to the same as the fill. This is a good method for making sure you get very pure colors all the way to the edges of polygon borders - and to avoid AA artifacts. And I think it looks good. But you may also be interested in not using a line at all and setting the polygon-gamma to something like .5 or .6. Any value for gamma under 1 reduces the level of AA and therefore reduces the artifacts.

Yeah, exactly, I was not aware of this parameter when I wrote this gist. Now I use 0.6 for gamma : )
Thx!

right on.