Examine source code of Medium Blue

{
  "name": "Medium Blue",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "Firefox Theme.png"
    },
    "colors": {
      "frame": "rgba(66, 88, 138, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(115, 122, 158, 1)",
      "toolbar_field": "rgba(230, 230, 230, 1)",
      "tab_line": "rgba(230, 230, 230, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{45754806-12a2-4adf-865a-01230d406318}"
    }
  }
}