Examine source code of TetoDarkMode

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "TetoDarkMode",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(34, 34, 34)",
      "toolbar_text": "rgb(216, 0, 67)",
      "frame": "rgb(26, 26, 26)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(230, 0, 64)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(230, 0, 64)",
      "popup": "rgb(216, 0, 67)",
      "popup_text": "rgb(255, 255, 255)",
      "tab_loading": "rgb(230, 0, 64)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{88a2eaef-a2d9-4a20-bcd2-40d2d53ec556}"
    }
  }
}