Examine source code of Nice dark color

{
  "name": "Nice dark color",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "1920x1080-black-solid-color-background.jpeg"
    },
    "colors": {
      "frame": "rgba(0, 0, 0, 1)",
      "tab_background_text": "rgba(242, 0, 0, 1)",
      "toolbar": "rgba(0, 0, 0, 1)",
      "bookmark_text": "rgba(255, 0, 0, 1)",
      "toolbar_field": "rgba(130, 0, 0, 1)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(250, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1f91f3d4-1c43-45b3-a821-881daccd9146}"
    }
  }
}