Examine source code of Four20

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#310ceb",
      "tab_background_text": "#0bd63e"
    }
  },
  "version": "2.0",
  "name": "Four20",
  "manifest_version": 2,
  "description": "The Best 420 Theme, Get High Just Looking at those juicy Buds"
}