Examine source code of Alpenglow Dark

{
  "manifest_version": 2,
  "name": "Alpenglow Dark",
  "description": "The Firefox Alpenglow theme modified so that it will always use its dark variant.",
  "version": "1.2",
  "icons": {
    "32": "icon.svg"
  },
  "theme": {
    "images": {
      "additional_backgrounds": [
        "background-noodles-right-dark.svg",
        "background-noodles-left-dark.svg",
        "background-gradient-dark.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top",
        "left top",
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "no-repeat",
        "no-repeat",
        "repeat-x"
      ],
      "zap_gradient": "linear-gradient(90deg, #9059FF 0%, #FF4AA2 52.08%, #FFBD4F 100%)"
    },
    "colors": {
      "frame": "#291D4F",
      "toolbar": "hsla(254, 46%, 21%, .96)",
      "button_background_active": "hsla(255, 100%, 94%, .24)",
      "button_background_hover": "hsla(255, 100%, 94%, .12)",
      "icons": "hsla(271, 100%, 77%, 1)",
      "icons_attention": "hsla(157, 100%, 66%, 1)",
      "toolbar_text": "hsla(255, 100%, 94%, 1)",
      "toolbar_vertical_separator": "hsla(271, 100%, 77%, .4)",
      "toolbar_field": "hsla(250, 43%, 25%, 1)",
      "toolbar_field_focus": "hsla(250, 43%, 25%, .98)",
      "toolbar_field_text": "hsla(255, 100%, 94%, 1)",
      "toolbar_field_text_focus": "hsla(255, 100%, 94%, 1)",
      "toolbar_field_border": "transparent",
      "toolbar_field_border_focus": "hsla(265, 100%, 72%, 1)",
      "toolbar_field_highlight": "hsla(265, 100%, 72%, .32)",
      "toolbar_top_separator": "transparent",
      "toolbar_bottom_separator": "hsla(245, 38%, 33%, .96)",
      "bookmark_text": "hsla(255, 100%, 94%, 1)",
      "tab_selected": "rgb(60, 31, 123)",
      "tab_text": "hsla(255, 100%, 94%, 1)",
      "tab_background_text": "hsla(255, 100%, 94%, 1)",
      "tab_background_separator": "hsla(255, 100%, 94%, 1)",
      "tab_line": "hsla(265, 100%, 72%, 1)",
      "tab_loading": "hsla(265, 100%, 72%, 1)",
      "ntp_background": "#2A2A2E",
      "ntp_text": "hsla(255, 100%, 94%, 1)",
      "popup": "hsla(250, 43%, 25%, 1)",
      "popup_text": "hsla(255, 100%, 94%, 1)",
      "popup_border": "hsla(255, 100%, 94%, .32)",
      "popup_highlight": "hsla(255, 100%, 94%, .12)",
      "popup_highlight_text": "hsla(0, 0%, 100%, 1)",
      "sidebar": "hsla(250, 43%, 25%, 1)",
      "sidebar_text": "hsla(255, 100%, 94%, 1)",
      "sidebar_border": "hsla(255, 100%, 94%, .24)",
      "sidebar_highlight": "hsla(259, 76%, 58%, 1)",
      "sidebar_highlight_text": "hsla(0, 0%, 100%, 1)",
      "focus_outline": "hsla(265, 100%, 72%, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9b615f11-c3a3-46bd-97a8-1721bb8122b9}"
    }
  }
}