Examine source code of Contemplating the Moon

{
  "name": "Contemplating the Moon",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "DP-31997-001-NEW.jpg"
    },
    "colors": {
      "frame": "rgba(38, 36, 35, 0)",
      "tab_background_text": "rgba(140, 129, 119, 1)",
      "toolbar": "rgba(71, 68, 68, 0)",
      "bookmark_text": "rgba(99, 112, 95, 1)",
      "toolbar_field": "rgba(59, 51, 44, 1)",
      "toolbar_field_text": "rgba(140, 129, 119, 1)",
      "tab_line": "rgba(131, 150, 126, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{8095abfc-291d-4855-b9e5-5fd0bbe92e16}"
    }
  }
}