Examine source code of Calm Afternoon

{
  "name": "Calm Afternoon",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "Firefox Theme 22.01.jpg"
    },
    "colors": {
      "frame": "rgba(0, 0, 0, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(80, 173, 14, 0.24)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(229, 255, 214, 0.67)",
      "toolbar_field_text": "rgba(3, 3, 3, 1)",
      "tab_line": "rgba(0, 0, 0, 1)"
    }
  }
}