Examine source code of Sakura Rabbit〜桜うさぎ

{
  "name": "Sakura Rabbit〜桜うさぎ",
  "manifest_version": 2,
  "version": "1.0",
  "theme": {
    "images": {
      "theme_frame": "3000×200_Firefox2020年3月分(完成形・350dpi).png"
    },
    "colors": {
      "frame": "rgba(252, 228, 244, 1)",
      "tab_background_text": "rgba(209, 52, 89, 1)",
      "toolbar": "rgba(255, 255, 255, 0.2)",
      "bookmark_text": "rgba(209, 52, 89, 1)",
      "toolbar_field": "rgba(255, 255, 255, 0.2)",
      "toolbar_field_text": "rgba(209, 52, 89, 1)"
    }
  }
}