Examine source code of Lean Dark

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "lean dark",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(28, 27, 34)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(215, 226, 239)",
      "toolbar_field": "rgb(54, 58, 89)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(205, 35, 185)",
      "popup": "rgb(28, 27, 34)",
      "popup_text": "rgb(215, 226, 239)",
      "toolbar_bottom_separator": "rgba(37, 150, 190, 0.51)",
      "toolbar_top_separator": "rgba(37, 150, 190, 0.51)",
      "tab_loading": "rgb(205, 35, 185)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{047f91b0-05c9-4d77-b11d-eb778d6f4740}"
    }
  }
}