Examine source code of Alumetal 2

{
  "name": "Alumetal 2",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#354857",
      "tab_background_text": "rgba(54, 148, 255, 1)",
      "toolbar": "rgba(0, 48, 110, 0.68)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(136, 138, 145, 0.63)",
      "toolbar_field_text": "rgba(54, 148, 255, 1)",
      "tab_line": "rgba(28, 98, 189, 1)"
    }
  }
}