Examine source code of Vampire Baseball

{
  "name": "Vampire Baseball",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "VampireBaseball-Header.jpg"
    },
    "colors": {
      "toolbar": "rgba(0, 0, 0, 0)",
      "toolbar_field": "rgba(0, 0, 0, 0)",
      "toolbar_field_text": "rgba(229, 255, 247, 1)",
      "frame": "#1b434b",
      "tab_background_text": "rgba(204, 255, 238, 1)"
    }
  }
}