Examine source code of YouTube Dark Mode Theme

{
  "manifest_version": 2,
  "version": "2.0",
  "name": "Youtube Dark Theme",
  "theme": {
    "images": {},
    "properties": {},
    "colors": {
      "toolbar": "rgb(38, 38, 38)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(15, 15, 15)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(38, 38, 38)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(255, 255, 255)",
      "popup": "rgb(15, 15, 15)",
      "popup_text": "rgb(255, 255, 255)",
      "ntp_background": "rgb(15, 15, 15)",
      "sidebar_border": "rgba(15, 15, 15, 0)",
      "tab_loading": "rgb(255, 255, 255)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{503e173b-1b25-413e-9d71-f2b9ee8366b8}"
    }
  }
}