Examine source code of Shapla at Dawn

{
  "name": "Shapla at Dawn",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(54, 86, 79, 1)",
      "tab_background_text": "rgba(228, 241, 234, 1)",
      "toolbar": "rgba(63, 101, 91, 0.48)",
      "bookmark_text": "rgba(241, 250, 246, 1)",
      "toolbar_field": "rgba(22, 57, 48, 0.78)",
      "toolbar_field_text": "rgba(217, 238, 228, 1)",
      "tab_line": "rgba(217, 174, 126, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "shapla-at-dawn-nature@firefox.theme"
    }
  }
}