Examine source code of Spring Into Summer

{
  "name": "Spring Into Summer",
  "manifest_version": 2,
  "version": "3.0",
  "theme": {
    "images": {
      "theme_frame": "SpringIntoSummerH.jpg"
    },
    "colors": {
      "frame": "rgba(114, 138, 173, 1)",
      "tab_background_text": "rgba(255, 255, 255, 1)",
      "toolbar": "rgba(76, 120, 191, 0.44)",
      "bookmark_text": "rgba(255, 255, 255, 1)",
      "toolbar_field": "rgba(77, 109, 161, 0.12)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)",
      "tab_line": "rgba(255, 255, 255, 1)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{baa4b744-f427-47fa-becd-adc2115a2290}"
    }
  }
}