Examine source code of Superman Calm Blue

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Superman Calm Blue",
  "manifest_version": 2,
  "description": "Credit to <a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/06b403fdfacb2666436b55745eb97d1ab946ea806e01f3fdbba09ff65fce1489/http%3A//VectorTemplates.com\">VectorTemplates.com</a> for Superman logo vector."
}