Examine source code of Undertale Keeping fun

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#000"
    }
  },
  "version": "2.0",
  "name": "Undertale Keeping fun",
  "manifest_version": 2,
  "description": "I love Undertale! If you love Undertale and Sans then this is the theme for you it tells you a little bit about the game :-)!"
}