Examine source code of Leo's Black Theme

{
  "name": "Big Black",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "black_background_photo_print-r5d1d633ef2b0471aaf0266679c1f0b52_xpua7_8byvr_307.jpg"
    },
    "colors": {
      "frame": "rgba(42, 42, 42, 1)",
      "tab_background_text": "rgba(0, 0, 0, 1)",
      "toolbar": "rgba(42, 42, 42, 1)",
      "bookmark_text": "rgba(64, 64, 64, 1)",
      "toolbar_field": "rgba(0, 0, 0, 1)",
      "toolbar_field_text": "rgba(64, 64, 64, 1)"
    }
  }
}