Examine source code of GMG V2

{
  "name": "GMG V2",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "GMG_Persona.jpg"
    },
    "colors": {
      "frame": "#000000",
      "tab_background_text": "#ffd000",
      "toolbar": "rgba(204, 177, 25, 0.5)",
      "bookmark_text": "rgba(0, 0, 0, 1)",
      "toolbar_field": "rgba(219, 216, 192, 1)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(0, 0, 0, 1)"
    }
  }
}