Examine source code of Borderless White

{
  "name": "Borderless white",
  "description": "Unified simple white theme that removes borders",
  "homepage_url": "https://github.com/andreicristianpetcu/firefox_themes",
  "author": "Andrei Cristian Petcu",
  "manifest_version": 2,
  "version": "1.4",
  "icons": {
    "16": "icon-16.png",
    "48": "icon-48.png",
    "96": "icon-96.png",
    "128": "icon-128.png"
  },
  "theme": {
    "colors": {
      "frame": "#FFFFFF",
      "ntp_background": "#FFFFFF",
      "tab_background_separator": "#FFFFFF",
      "tab_background_text": "#111",
      "tab_selected": "#FFFFFF",
      "toolbar_bottom_separator": "#FFFFFF",
      "toolbar_field_border_focus": "rgba(12, 12, 13, 0.25)",
      "toolbar_field_border": "white",
      "popup": "white",
      "popup_border": "white",
      "popup_highlight_text": "rgb(17, 17, 17)",
      "popup_highlight": "rgba(12, 12, 13, 0.15)",
      "popup_text": "rgb(17, 17, 17)",
      "toolbar_field_separator": "white"
    }
  }
}