Examine source code of progressive-minimal

{
  "theme": {
    "images": {
      "theme_frame": "K_410_by.jpg"
    },
    "colors": {
      "frame": "#8f300a",
      "tab_background_text": "#542904"
    }
  },
  "version": "2.0",
  "name": "progressive-minimal",
  "manifest_version": 2
}