Examine source code of Matte black theme rb

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Thème noir mat",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(50, 52, 58)",
      "toolbar_text": "rgb(189, 191, 193)",
      "frame": "rgb(33, 35, 39)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(32, 34, 39)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(50, 52, 58)",
      "popup": "rgb(50, 52, 58)",
      "popup_text": "rgb(231, 231, 231)",
      "button_background_hover": "rgb(74, 76, 83)",
      "icons": "rgb(231, 231, 231)",
      "ntp_background": "rgb(203, 203, 203)",
      "tab_loading": "rgb(50, 52, 58)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{41d004f2-3204-449a-a4c4-1594080134c9}"
    }
  }
}