Examine source code of Dark Theme Basic

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Dark Theme Basic",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(32, 32, 32)",
      "toolbar_text": "rgb(244, 244, 244)",
      "frame": "rgb(8, 8, 8)",
      "tab_background_text": "rgb(134, 134, 134)",
      "toolbar_field": "rgb(40, 40, 40)",
      "toolbar_field_text": "rgb(162, 162, 162)",
      "tab_line": "rgb(8, 8, 8)",
      "popup": "rgb(43, 43, 43)",
      "popup_text": "rgb(143, 143, 143)",
      "button_background_active": "rgb(89, 89, 89)",
      "button_background_hover": "rgb(86, 86, 86)",
      "icons": "rgb(146, 146, 146)",
      "ntp_background": "rgb(19, 19, 19)",
      "popup_border": "rgb(44, 44, 44)",
      "sidebar_border": "rgb(44, 44, 44)",
      "sidebar_highlight_text": "rgb(165, 165, 165)",
      "sidebar_text": "rgb(181, 181, 181)",
      "sidebar": "rgb(44, 44, 44)",
      "tab_text": "rgb(206, 206, 206)",
      "toolbar_bottom_separator": "rgb(8, 8, 8)",
      "toolbar_field_border_focus": "rgb(64, 64, 64)",
      "toolbar_field_border": "rgb(32, 32, 32)",
      "toolbar_top_separator": "rgb(8, 8, 8)",
      "tab_loading": "rgb(8, 8, 8)"
    }
  }
}