The CTRL key on Macintosh computers…
The CTRL key on Macintosh computers are frequently used as a key to activate mouse scroll to globally zoom the whole screen. (In later versions, it has to be activated in the accessibilities settings.) The CTRL key on many browsers on Windows machines is used to change the zoom level inside the browser. It seems that Vivaldi is also assigning the CTRL key to zoom inside web pages, so I get a combined effect, which is shrinking the text as I zoom in... Don't worry. This was also a problem in Google Chrome about a year ago. I think they solved it by not using the CTRL key for anything at all, at least not on Macs, only allow zooming with CMD + "+" and "-" buttons. As I use the global zoom all the time, it was annoying enough that I stopped using Chrome for a while when that was a problem there.