@leocg
Those keys are far from home position, so I don't want to use those.

@jojo0587 thank you for your reply.

First of all, I want to use keyboard for browsing, not mouse.
And this browser let me change preference for lots of shortcuts and accepts single key shortcuts.
So I can set almost all preferred (adopted vimperator) shortcuts including history back to h or focus to address bar to o.
But there is no config for scrolling down (space) and scrolling up (s-space), close tab(c-w).

Vivaldi can change those configs, but that browser has some problem for my usage and I want to use Opera.
So I am very glad if I can change those configs.

I am ex-vimperator-user and i am glad if there is shortcut configs for those three.

The smooth scrolling preference on opera://flags is not available on macOS.
Is there any way to disable it?