Examine source code of Forsythia..

{
  "name": "Forsythia..",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "ForsythiaH.jpg"
    },
    "colors": {
      "frame": "rgba(250, 245, 155, 1)",
      "tab_background_text": "rgba(0, 0, 0, 1)",
      "toolbar": "rgba(255, 253, 163, 0)",
      "bookmark_text": "rgba(0, 0, 0, 1)",
      "toolbar_field": "rgba(255, 255, 163, 0.08)",
      "toolbar_field_text": "rgba(0, 0, 0, 1)",
      "tab_line": "rgba(0, 0, 0, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b0f6f693-309b-4d05-b38e-33fe70e90006}"
    }
  }
}