Examine source code of Moon and Cosmos

{
  "name": "Moon and Cosmos",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "3000×200Firefox2019_8月分(完成形2・350dpi).png"
    },
    "colors": {
      "frame": "rgba(255, 218, 245, 1)",
      "tab_background_text": "rgba(255, 139, 228, 1)",
      "toolbar": "rgba(255, 255, 255, 0.2)",
      "bookmark_text": "rgba(255, 139, 228, 1)",
      "toolbar_field": "rgba(255, 255, 255, 0.2)",
      "toolbar_field_text": "rgba(255, 139, 228, 1)"
    }
  }
}