One of the possible reasons that it mess up your website web design, is that you use not the latest Turn Off the Lights browser extension version on your computer. And that the “Flash Detection” feature is enabled in the Turn Off the Lights options page.
Fix the web design
To fix this issue go and reinstall the Turn Off the Lights browser extension from the official website. And disable the “Flash Detection” in the options page, tab “Advanced Options”.
- Click right on the gray lamp button in your omnibox or workbar.
- Select “Options” from the menu.
- Right click you on “Advanced Options”.
- And select the radio button from the “Flash Detection” feature to “disabled”.
- Restart your browser.