Examine source code of Gray Mode

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Thulium Theme",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-001-9c6d74e14860e77ee6f8f43e824bff25.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(0, 0, 0, 0.23)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(106, 110, 113)",
      "tab_background_text": "rgb(190, 197, 195)",
      "toolbar_field": "rgba(75, 77, 79, 0.08)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(255, 255, 255)",
      "popup": "rgba(0, 0, 0, 0.43)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_hover": "rgba(49, 55, 55, 0.57)",
      "icons": "rgba(255, 255, 255, 0.87)",
      "ntp_background": "rgba(0, 0, 0, 0.87)",
      "ntp_text": "rgba(255, 255, 255, 0.87)",
      "tab_selected": "rgba(124, 133, 126, 0.15)",
      "tab_text": "rgb(255, 255, 255)",
      "toolbar_field_separator": "rgb(255, 255, 255)",
      "toolbar_top_separator": "rgba(255, 255, 255, 0)",
      "toolbar_vertical_separator": "rgba(255, 255, 255, 0)",
      "tab_loading": "rgb(255, 255, 255)"
    }
  }
}