Examine source code of Formula E

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#10234B",
      "tab_background_text": "#02BDC7"
    }
  },
  "version": "2.0",
  "name": "Formula E",
  "manifest_version": 2,
  "description": "An unofficial Formula E theme for Firefox, styled after the in-race infographics, featuring the Formula E logo."
}