Examine source code of Adwaita-Night

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Adwaita-Night",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center top"
      ],
      "additional_backgrounds_tiling": [
        "repeat-x"
      ]
    },
    "colors": {
      "toolbar": "rgb(49, 49, 49)",
      "toolbar_text": "rgb(229, 229, 227)",
      "frame": "rgb(38, 38, 38)",
      "tab_background_text": "rgb(104, 104, 104)",
      "toolbar_field": "rgb(45, 44, 46)",
      "toolbar_field_text": "rgb(229, 229, 227)",
      "tab_line": "rgb(66, 66, 66)",
      "popup": "rgb(53, 53, 53)",
      "popup_text": "rgb(229, 229, 227)",
      "tab_loading": "rgb(66, 66, 66)"
    }
  }
}