Examine source code of Castlevania NES

{
  "name": "Castlevania NES",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(4, 6, 31, 0.35)",
      "tab_background_text": "rgba(105, 200, 219, 1)",
      "toolbar": "rgba(82, 89, 10, 0)",
      "bookmark_text": "rgba(22, 222, 55, 0.72)",
      "toolbar_field": "rgba(3, 3, 3, 0.78)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)"
    }
  }
}