Examine source code of Basic dark blue

{
  "name": "Basic dark blue",
  "manifest_version": 2,
  "version": "4.0",
  "theme": {
    "images": {
      "theme_frame": "firefox_ga1azKodSz.png"
    },
    "colors": {
      "frame": "rgba(7, 30, 79, 1)",
      "tab_background_text": "rgba(184, 184, 184, 1)",
      "toolbar": "rgba(110, 110, 110, 1)",
      "bookmark_text": "rgba(255, 255, 255, 0.97)",
      "toolbar_field": "rgba(145, 145, 145, 1)",
      "toolbar_field_text": "rgba(79, 79, 79, 1)"
    }
  }
}