Examine source code of Pro Gray

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Pro Grey",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(227, 227, 227)",
      "toolbar_text": "rgb(79, 79, 79)",
      "frame": "rgb(101, 102, 99)",
      "tab_background_text": "rgb(163, 163, 163)",
      "toolbar_field": "rgba(255, 255, 255, 0.53)",
      "toolbar_field_text": "rgb(34, 43, 67)",
      "tab_line": "rgb(102, 102, 102)",
      "popup": "rgb(231, 242, 244)",
      "popup_text": "rgb(84, 84, 84)",
      "tab_loading": "rgb(102, 102, 102)"
    }
  }
}