Cross-browser compatibility

Themes for Firefox are not always compatible with other major browsers.

There is currently limited compatibility between themes in the major browsers. Opera takes an entirely different approach, and Microsoft Edge themes are not yet open to developers.

There is good compatibility between Firefox static themes and Chrome themes, providing the ability to port a single header image theme from Firefox to Chrome. However, noting that frame and tab_background_text only support RGB color array definition on Chrome.

So, in the single image theme example (weta_fade) could be supported in Chrome using the following manifest.json file:

  "manifest_version": 2,
  "version": "1.0",
  "name": "<your_theme_name>",
  "theme": {
    "images": {
      "theme_frame": "weta.png"
    "colors": {
      "frame": [ 173 , 176 , 159 ],
      "tab_background_text": [ 0 , 0 , 0 ]

Also, note that Chrome tiles the “theme_frame”: image from the left of the header area:


For more information, see the notes on Chrome compatibility on MDN.