Examine source code of Focus Dark

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Focus Dark",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "left center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(45, 35, 87)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(27, 17, 51)",
      "tab_background_text": "rgb(236, 232, 251)",
      "toolbar_field": "rgb(57, 51, 115)",
      "toolbar_field_text": "rgb(194, 193, 225)",
      "tab_line": "rgb(161, 85, 245)",
      "popup": "rgb(54, 37, 92)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_active": "rgb(161, 85, 245)",
      "button_background_hover": "rgb(255, 161, 99)",
      "icons_attention": "rgb(255, 161, 99)",
      "ntp_background": "rgb(28, 21, 55)",
      "popup_border": "rgb(161, 85, 245)",
      "tab_loading": "rgb(255, 161, 99)",
      "toolbar_bottom_separator": "rgb(188, 99, 255)",
      "toolbar_field_border_focus": "rgb(255, 161, 99)",
      "toolbar_field_focus": "rgb(42, 29, 80)",
      "toolbar_field_highlight_text": "rgb(255, 255, 255)",
      "toolbar_field_highlight": "rgb(148, 81, 238)",
      "toolbar_field_text_focus": "rgb(255, 255, 255)",
      "toolbar_vertical_separator": "rgb(148, 81, 238)"
    }
  }
}