Examine source code of Grayed In & Out

{
  "manifest_version": 2,
  "version": "2.0",
  "name": "Grayed In & Out",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-010-e9f94a3e61666a4c7677eb9cce17d854.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(227, 227, 227)",
      "toolbar_text": "rgb(0, 0, 0)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(252, 252, 252)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(0, 0, 0)",
      "tab_line": "rgb(255, 0, 23)",
      "popup": "rgb(227, 227, 227)",
      "popup_text": "rgb(0, 0, 0)",
      "icons_attention": "rgb(255, 0, 4)",
      "popup_border": "rgb(0, 0, 0)",
      "tab_selected": "rgb(251, 251, 251)",
      "toolbar_bottom_separator": "rgb(0, 0, 0)",
      "toolbar_field_border": "rgb(0, 0, 0)",
      "toolbar_top_separator": "rgb(0, 0, 0)",
      "tab_loading": "rgb(255, 0, 23)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{40969fb1-b6cd-442e-b80e-2fe280fa483f}"
    }
  }
}