With Opera, you can do something similar to Firefox add-on called Greasemonkey.
Greasemonkey is used to customize webpage to be displayed as your own preference. However, if you’re not Firefox user, you also can do this by using Opera.
How to do that? Let’s explore those steps.
If you haven’t had Opera web browser, you can find and download it for free here.
Now, open your Opera and then go to Apple ▸ Opera ▸ Preferences… Then you will be brought into Opera Preferences, on the General Section.
Now, go to the Advanced section. On the sidebar you will see some sections. Choose on Content then click on the button labelled