Examine source code of Adwaita-Dark

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Adwaita Dark",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(51, 51, 51)",
      "toolbar_text": "rgb(229, 229, 227)",
      "frame": "rgb(42, 42, 42)",
      "tab_background_text": "rgb(195, 195, 192)",
      "toolbar_field": "rgb(51, 51, 51)",
      "toolbar_field_text": "rgb(229, 229, 227)",
      "tab_line": "rgb(51, 51, 51)",
      "popup": "rgb(53, 53, 53)",
      "popup_text": "rgb(190, 190, 189)",
      "button_background_active": "rgb(21, 83, 158)",
      "icons_attention": "rgb(21, 83, 158)",
      "ntp_background": "rgb(42, 42, 42)",
      "popup_highlight": "rgb(21, 83, 158)",
      "tab_loading": "rgb(21, 83, 158)",
      "toolbar_field_border_focus": "rgb(21, 83, 158)",
      "toolbar_field_border": "rgb(21, 83, 158)",
      "toolbar_field_highlight_text": "rgb(21, 83, 158)"
    }
  }
}