Examine source code of DarkV2

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "dark",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(32, 30, 33)",
      "toolbar_text": "rgb(216, 222, 233)",
      "frame": "rgb(25, 23, 26)",
      "tab_background_text": "rgb(216, 222, 233)",
      "toolbar_field": "rgb(25, 23, 26)",
      "toolbar_field_text": "rgb(216, 222, 233)",
      "tab_line": "rgba(216, 222, 233, 0.25)",
      "popup": "rgb(32, 30, 33)",
      "popup_text": "rgb(216, 222, 233)",
      "popup_highlight_text": "rgb(32, 30, 33)",
      "popup_highlight": "rgb(97, 128, 254)",
      "toolbar_field_border_focus": "rgba(255, 0, 0, 0)",
      "tab_loading": "rgba(216, 222, 233, 0.25)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b9e32567-df3f-47e3-8e0d-a5a2af05e33b}"
    }
  }
}