Examine source code of Persona 5

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Persona 5 Style",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(0, 0, 0)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(186, 0, 1)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(0, 0, 0)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(0, 0, 0)",
      "popup": "rgb(0, 0, 0)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_active": "rgb(186, 0, 1)",
      "button_background_hover": "rgb(0, 0, 0)",
      "frame_inactive": "rgb(0, 0, 0)",
      "icons_attention": "rgb(186, 0, 1)",
      "icons": "rgb(255, 255, 255)",
      "ntp_background": "rgb(0, 0, 0)",
      "ntp_text": "rgb(255, 255, 255)",
      "popup_border": "rgb(255, 255, 255)",
      "popup_highlight_text": "rgb(0, 0, 0)",
      "popup_highlight": "rgb(255, 255, 255)",
      "sidebar_border": "rgb(255, 255, 255)",
      "sidebar_highlight_text": "rgb(255, 255, 255)",
      "sidebar_highlight": "rgb(186, 0, 1)",
      "sidebar_text": "rgb(255, 255, 255)",
      "sidebar": "rgb(0, 0, 0)",
      "tab_loading": "rgb(186, 0, 1)",
      "tab_selected": "rgb(186, 0, 1)",
      "tab_text": "rgb(255, 255, 255)",
      "toolbar_bottom_separator": "rgb(0, 0, 0)",
      "toolbar_field_border_focus": "rgba(255, 255, 255, 0)",
      "toolbar_field_border": "rgb(0, 0, 0)",
      "toolbar_field_focus": "rgb(0, 0, 0)",
      "toolbar_field_highlight_text": "rgb(0, 0, 0)",
      "toolbar_field_highlight": "rgb(255, 255, 255)",
      "toolbar_field_separator": "rgb(255, 255, 255)",
      "toolbar_top_separator": "rgb(255, 255, 255)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{be7cf2f5-1cad-43c9-beb4-26f9ddb0fe95}"
    }
  }
}