Examine source code of Washed Marbles

{
  "name": "Washed Marbles",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "gh_0002d.jpg"
    },
    "colors": {
      "toolbar": "rgba(94, 115, 191, 0.42)",
      "toolbar_field": "rgba(77, 1, 0, 0.52)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)",
      "frame": "rgba(0, 0, 0, 1)",
      "tab_background_text": "rgba(252, 252, 252, 1)",
      "bookmark_text": "rgba(29, 47, 125, 0.92)"
    }
  }
}