You appear to have enabled Opera’s native ad blocker. The ad blocker inserts non-lethal elements in a page’s code to restructure the layout after blocking ads.
Each of these solutions will help in the order we suggest most:
- Ignore this <style> tag in the <head> tag ?
- Download and use either Opera Developer, Beta, or Portable for development (with ad blocker disabled), and use Opera Stable for web browsing
- Create a separate profile with ad blocker disabled
- Disable Opera’s native ad blocker
We decided not to hide our <style> tag because it would result in inconsistencies between what you see in DevTools and in the page, making debugging much harder.