Too small plus (+) sign with tabs to the left
The plus (+) sign to add a new tab at the bottom of the tabs pictures is too small. It should be an option to choose that the plus sign should be inside a square, and that a click anywhere in the square should activate the function. It is difficult to hit the button. (I know about keyboard shortcuts, but I like visual buttons better when they are available.)
@Wiking1 It's not only that you "like" visual buttons - sometimes you just don't have a keyboard (on a tablet for example) and those tiny UI buttons just make it very difficult to use the browser. Currently Vivaldi's UI is quite inconvenient to use on a touchscreen. I hope that they will take care of that too one day...