Examine source code of Among Us BG

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Among Us",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "left bottom"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(0, 0, 0, 0.23)",
      "toolbar_text": "rgb(0, 0, 0)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(143, 194, 131)",
      "toolbar_field": "rgba(106, 96, 95, 0.49)",
      "toolbar_field_text": "rgb(143, 147, 167)",
      "tab_line": "rgb(68, 75, 213)",
      "popup": "rgb(203, 207, 226)",
      "popup_text": "rgb(0, 0, 0)",
      "tab_loading": "rgb(68, 75, 213)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{00b2f6e0-a47d-4dc7-9e57-6b9cea78495d}"
    }
  }
}