Examine source code of Black Polygons

{
  "name": "Black Polygons",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "Black Polygons Background 01_preview1.jpg"
    },
    "colors": {
      "frame": "rgba(0, 0, 0, 0.82)",
      "tab_background_text": "rgba(0, 0, 0, 1)",
      "bookmark_text": "rgba(0, 0, 0, 0.91)",
      "toolbar_field": "rgba(255, 255, 255, 0.73)",
      "toolbar_field_text": "rgba(0, 0, 0, 0.81)",
      "tab_line": "rgba(0, 0, 0, 0.53)"
    }
  }
}