"#6baed6", "#9ecae1", "#c6dbef", "#e6550d",
            "#fd8d3c", "#fdae6b", "#fdd0a2", "#31a354", "#74c476",
            "#a1d99b", "#c7e9c0", "#756bb1", "#9e9ac8", "#bcbddc",
            "#dadaeb", "#636363", "#969696", "#bdbdbd", "#d9d9d9"
          ]
        },
        {
          "name": "size",
          "type": "ordinal",
          "domain": [0, 1, 2, 3],
          "range": [256, 28, 20, 14]
        },
        {
          "name": "opacity",
          "type": "ordinal",
          "domain": [0, 1, 2, 