Examine source code of pikachu(dark theme)

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "pikachu(dark theme)",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(51, 42, 42, 0)",
      "toolbar_text": "rgb(252, 219, 9)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgba(23, 23, 23, 0.34)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(247, 144, 106)",
      "popup": "rgb(0, 0, 0)",
      "popup_text": "rgb(250, 243, 9)",
      "tab_loading": "rgb(247, 144, 106)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f92e6fcb-e270-4d63-a3c9-91ae303839f9}"
    }
  }
}