Examine source code of Portal 2 Space Core

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Portal 2 Space Core",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(7, 50, 84, 0.6)",
      "toolbar_text": "rgb(230, 181, 50)",
      "frame": "rgb(6, 28, 48)",
      "tab_background_text": "rgb(230, 181, 50)",
      "toolbar_field": "rgb(48, 77, 102)",
      "toolbar_field_text": "rgb(249, 214, 66)",
      "tab_line": "rgb(230, 181, 50)",
      "popup": "rgb(7, 50, 84)",
      "popup_text": "rgb(216, 173, 103)",
      "tab_loading": "rgb(230, 181, 50)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{8a232446-a44f-424a-8d6e-4fce630094ee}"
    }
  }
}