Examine source code of dark-only-when-active

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "dark-only-when-active",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(58, 89, 105, 0.17)",
      "toolbar_text": "rgb(247, 253, 251)",
      "frame": "rgb(19, 32, 36)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(90, 93, 154)",
      "tab_line": "rgb(218, 135, 124)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgb(90, 93, 154)",
      "frame_inactive": "rgb(43, 74, 85)",
      "tab_loading": "rgb(218, 135, 124)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{50b0d2b6-f8e0-466d-8be2-1717416991dd}"
    }
  }
}