Examine source code of iSSU Material Dark

{
  "theme": {
    "colors": {
      "tab_selected": "#1e222b",
      "toolbar": "#1e222b",
      "tab_text": "#c0bfbc",
      "frame": "#1e222b",
      "frame_inactive": "#1e222b",
      "sidebar_border": "#1e222b",
      "ntp_text": "#5e5c64",
      "tab_background_text": "#5e5c64",
      "ntp_background": "#1e222b",
      "sidebar": "#1e222b",
      "sidebar_highlight": "#1e222b",
      "tab_background_separator": "#1e222b",
      "button_background_hover": "#1e222b",
      "sidebar_text": "#3d3846",
      "sidebar_highlight_text": "#5e5c64",
      "button_background_active": "#1e222b",
      "icons": "#5e5c64",
      "popup": "#1e222b",
      "popup_highlight": "#241f31",
      "popup_text": "#77767b",
      "tab_loading": "#1e222b",
      "toolbar_field": "#1e222b",
      "toolbar_field_border_focus": "#5e5c64",
      "toolbar_field_text": "#9a9996",
      "toolbar_field_highlight": "#1e222b",
      "toolbar_field_separator": "#1e222b",
      "toolbar_top_separator": "#1e222b",
      "toolbar_vertical_separator": "#1e222b",
      "toolbar_text": "#9a9996",
      "toolbar_field_highlight_text": "#9a9996",
      "toolbar_field_text_focus": "#ffffff",
      "toolbar_field_focus": "#1e222b",
      "toolbar_field_border": "#1e222b",
      "toolbar_bottom_separator": "#1e222b",
      "tab_line": "#9a9996",
      "popup_highlight_text": "#77767b",
      "popup_border": "#1e222b",
      "icons_attention": "#9a9996"
    }
  },
  "name": "iSSU Dark",
  "manifest_version": 2,
  "version": "3.0",
  "description": "This theme was created by iSSU",
  "browser_specific_settings": {
    "gecko": {
      "id": "{4a5729e4-5594-4141-a4d2-d2af834ee136}"
    }
  }
}