Examine source code of Visiox!

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#000000",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Visiox!",
  "manifest_version": 2,
  "description": "Visioxes striking vividly across the theme expressing bright, exciting colours, contrasting the dark background. This will certainly give your Firefox browser the edge! We'll leave it up to your imagination to reveal it's abstract curiousness."
}