Examine source code of Twilight Blue

{
  "name": "Twilight Blue",
  "manifest_version": 2,
  "version": "4.0",
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(157, 209, 250, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(159, 209, 252, 0)",
      "bookmark_text": "rgba(255, 250, 250, 1)",
      "toolbar_field": "rgba(20, 37, 51, 1)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)",
      "tab_line": "rgba(255, 255, 255, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e4821909-8dd0-46db-8896-eeabe599be30}"
    }
  }
}