Requirements:
Extension:
Chrome: https://chrome.google.com/webstore/detail/custom-style-script/ecjfaoeopefafjpdgnfcjnhinpbldjij
Firefox:
Opera: https://addons.opera.com/en/extensions/details/custom-style-script/?display=en
Extension's script(Code section): https://greasyfork.org/en/scripts/17111-nagytibor-xyz-gabe-n-tibi
Go to extension's settings and change about:blank to "http://nagytibor.xyz/" and copy script to textarea saying "Add JS code.". In the end click on the plus button to add the new rule