Examine source code of Dark plain simple elegant

{
  "manifest_version": 2,
  "version": "6.0",
  "name": "Ya",
  "theme": {
    "colors": {
      "toolbar": "rgb(28, 28, 28)",
      "toolbar_field_focus": "rgb(28, 28, 28)",
      "toolbar_field_border": "rgb(28, 28, 28)",
      "toolbar_text": "rgb(200, 200, 200)",
      "frame": "rgb(18, 18, 18)",
      "frame_inactive": "rgb(18, 18, 18)",
      "tab_background_text": "rgb(110, 110, 110)",
      "toolbar_field": "rgb(28, 28, 28)",
      "toolbar_field_text": "rgb(200, 200, 200)",
      "tab_line": "rgb(28, 28, 28)",
      "popup": "rgb(28, 28, 28)",
      "popup_text": "rgb(200, 200, 200)",
      "icons_attention": "rgb(200, 200, 200)",
      "icons": "rgb(110, 110, 110)",
      "ntp_background": "rgb(24, 24, 24)",
      "ntp_text": "rgb(255, 255, 255)",
      "popup_border": "rgb(28, 28, 28)",
      "toolbar_field_border_focus": "rgb(28, 28, 28)",
      "toolbar_top_separator": "rgb(18, 18, 18)",
      "toolbar_bottom_separator": "rgb(18, 18, 18)",
      "tab_loading": "rgb(28, 28, 28)",
      "tab_selected": "rgb(28, 28, 28)",
      "tab_text": "rgb(200, 200, 200)",
      "sidebar": "rgb(18, 18, 18)",
      "sidebar_text": "rgb(200, 200, 200)",
      "button_background_active": "rgb(57, 57, 57)",
      "button_background_hover": "rgb(57, 57, 57)",
      "sidebar_border": "rgb(28, 28, 28)",
      "sidebar_highlight_text": "rgb(200, 200, 200)",
      "sidebar_highlight": "rgb(18, 18, 18)",
      "toolbar_field_text_focus": "rgb(200, 200, 200)",
      "toolbar_field_highlight_text": "rgb(200, 200, 200)",
      "toolbar_field_highlight": "rgb(57, 57, 57)",
      "popup_highlight_text": "rgb(200, 200, 200)",
      "popup_highlight": "rgb(57, 57, 57)",
      "toolbar_vertical_separator": "rgb(200, 200, 200)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7939836e-e28b-4f07-8f9c-c4aeb786a5cc}"
    }
  }
}