Examine source code of _black

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "_black",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(48, 48, 50)",
      "toolbar_text": "rgb(94, 224, 228)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(253, 248, 236)",
      "toolbar_field": "rgb(32, 33, 35)",
      "toolbar_field_text": "rgb(255, 234, 195)",
      "tab_line": "rgba(0, 0, 0, 0.27)",
      "popup": "rgba(31, 31, 32, 0.87)",
      "popup_text": "rgb(254, 240, 215)",
      "button_background_active": "rgb(31, 31, 31)",
      "button_background_hover": "rgb(31, 31, 31)",
      "popup_border": "rgb(31, 31, 31)",
      "toolbar_top_separator": "rgb(25, 26, 28)",
      "tab_loading": "rgba(0, 0, 0, 0.27)"
    }
  }
}