Examine source code of Gruvbox in Space

{
  "name": "Gruvbox in Space",
  "description": "Good old Gruvbox mixed with the popular Firefox Dark-Space theme",
  "homepage_url": "https://github.com/davidk55/gruvbox-in-space",
  "manifest_version": 2,
  "version": "1.1",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/space.gif"
      ]
    },
    "properties": {
      "additional_backgrounds_tiling": [
        "repeat-x"
      ]
    },
    "colors": {
      "frame": "#282828",
      "popup": "#282828",
      "popup_text": "#ebdbb2",
      "popup_highlight": "#458588",
      "tab_text": "#ebdbb2",
      "tab_line": "rgba(0, 0, 0, 0)",
      "tab_selected": "rgba(235, 219, 178, 0.3)",
      "tab_background_text": "#ebdbb2",
      "toolbar": "rgba(0, 0, 0, 0)",
      "toolbar_field": "#ebdbb2",
      "toolbar_field_highlight": "#458588",
      "toolbar_vertical_separator": "rgba(235, 219, 178, 0.3)",
      "sidebar": "#282828",
      "sidebar_highlight": "#458588",
      "sidebar_text": "#ebdbb2",
      "icons_attention": "#d79921",
      "bookmark_text": "#ebdbb2"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7f89affd-9149-459d-9971-86826ceb56f3}"
    }
  }
}