I'm not sure if the only options are:
Enlarge the window.
Use this or an equivalent extension.
Windows 10 (x64) | Anniversary Update
Opera Stable · Beta · Developer
Test profile | Back up Linux · Mac · Win
Hey thanks for replying. I already use stylish extension for many sites, I have tried other minimalistic scrollbars before but it didn't work. The link you provided worked! Many thanks, you have gotten rid of my annoyance of the scrollbar.