Prevent zooming of the Assistant icon

[ameshkov]

https://forum.adguard.com/index.php?threads/facelift-of-assistant.28054/#post-164784

Got a feature request on the forum. We'll be discussed there.

Technically possible:https://stackoverflow.com/questions/15233076/prevent-that-a-fixed-element-resizes-when-zooming-on-touchscreen