Get page HTML/CSS source code from browser

I want to be able to get page source code (html+css) while using it in browser.

For example, let's assume I'm on page google.com and my program is able to see what page source code is. After I type some request in search bar, I would also like to see changes from my program.

The program is supposed to be written on Python or C++.

Is there any frameworks or utils for such task?