Examine source code of blackyellowtheme

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "black/yellow theme",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-000-5672c42860d5b06e1058dc477397f3ef.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(59, 55, 56)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(255, 204, 0)",
      "tab_background_text": "rgb(0, 0, 0)",
      "toolbar_field": "rgb(37, 37, 40)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(88, 88, 88)",
      "popup": "rgb(59, 55, 56)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_hover": "rgb(74, 71, 72)",
      "icons": "rgb(88, 88, 88)",
      "tab_text": "rgb(255, 255, 255)",
      "toolbar_bottom_separator": "rgb(88, 88, 88)",
      "tab_loading": "rgb(88, 88, 88)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{39f88181-d751-44a0-a27a-ff098c3541f5}"
    }
  }
}