Examine source code of dark_black_grid

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "dark_black_grid",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(255, 255, 255, 0)",
      "toolbar_text": "rgb(0, 0, 0)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgba(42, 51, 62, 0)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(42, 51, 62)",
      "popup": "rgb(24, 24, 24)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_active": "rgba(255, 255, 255, 0)",
      "tab_selected": "rgb(255, 255, 255)",
      "tab_text": "rgb(0, 0, 0)",
      "toolbar_field_border_focus": "rgb(145, 145, 145)",
      "toolbar_field_border": "rgba(255, 255, 255, 0)",
      "toolbar_field_focus": "rgb(24, 24, 24)",
      "toolbar_field_highlight_text": "rgb(0, 0, 0)",
      "toolbar_field_highlight": "rgb(255, 255, 255)",
      "toolbar_field_text_focus": "rgb(255, 255, 255)",
      "tab_loading": "rgb(42, 51, 62)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1f87699b-e6a3-4b19-a94a-3763bc3d9280}"
    }
  }
}