Examine source code of Flatabulous

{
  "description": "Dark gray theme that matches Flatabulous Ubuntu theme.",
  "manifest_version": 2,
  "name": "Flatabulous",
  "version": "1.3resigned1",
  "homepage_url": "https://github.com/anibyl/firefox-flatabulous",
  "theme": {
    "images": {
      "headerURL": "1px.png",
      "theme_frame": "1px.png"
    },
    "colors": {
      "accentcolor": [
        34,
        34,
        34
      ],
      "button_background_active": [
        34,
        34,
        34
      ],
      "button_background_hover": [
        51,
        51,
        51
      ],
      "icons": [
        255,
        255,
        255
      ],
      "icons_attention": [
        255,
        255,
        255
      ],
      "popup": [
        51,
        51,
        51
      ],
      "popup_border": [
        51,
        51,
        51
      ],
      "popup_highlight": [
        122,
        125,
        129
      ],
      "popup_highlight_text": [
        255,
        255,
        255
      ],
      "popup_text": [
        255,
        255,
        255
      ],
      "tab_line": [
        51,
        51,
        51
      ],
      "tab_loading": [
        255,
        255,
        255
      ],
      "tab_selected": [
        51,
        51,
        51
      ],
      "tab_text": [
        255,
        255,
        255
      ],
      "textcolor": [
        255,
        255,
        255
      ],
      "toolbar": [
        51,
        51,
        51
      ],
      "toolbar_bottom_separator": [
        51,
        51,
        51
      ],
      "toolbar_field": [
        34,
        34,
        34
      ],
      "toolbar_field_border": [
        34,
        34,
        34
      ],
      "toolbar_field_border_focus": [
        34,
        34,
        34
      ],
      "toolbar_field_focus": [
        34,
        34,
        34
      ],
      "toolbar_field_separator": [
        51,
        51,
        51
      ],
      "toolbar_field_text": [
        255,
        255,
        255
      ],
      "toolbar_field_text_focus": [
        255,
        255,
        255
      ],
      "toolbar_text": [
        255,
        255,
        255
      ],
      "toolbar_top_separator": [
        51,
        51,
        51
      ],
      "toolbar_vertical_separator": [
        51,
        51,
        51
      ],
      "bookmark_text": [
        255,
        255,
        255
      ],
      "frame": [
        34,
        34,
        34
      ],
      "frame_inactive": [
        34,
        34,
        34
      ],
      "tab_background_separator": [
        51,
        51,
        51
      ],
      "tab_background_text": [
        255,
        255,
        255
      ]
    }
  },
  "applications": {
    "gecko": {
      "id": "firefox-flatabulous@anibyl.org",
      "strict_min_version": "57.0"
    }
  }
}