Have compared the javascript alert notification from Firefox and Vivaldi on my website. Find Vivaldi's much clearer and more readable and better positioned. Hope Moziila will do something with this.
Ah, I see, there was only one screenshot attached.
To make this more actionable, it would be helpful to include screenshots from both Firefox and Vivaldi, along with an explanation of what Vivaldi does better. Specifically, it would be useful to know how Vivaldi makes the alert clearer, more readable, and better positioned.