Disable animated GIFs and moving images in Firefox, use solid background

• 1 Go to about:config
  
• 2 set image.animation_mode to none
  
• 3 set privacy.resistFingerprinting to true, it can disable some types of web-based tracking, which includes animations triggered by JavaScript or CSS
  
• 4 Use custom stylesheet extension
  * {
  background-image: none !important
  background-attachement: scroll important!
  }
  
• N You may use less restrictive stylesheet tailored to specific sites, or HTML elements.
  

References

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox
• https://addons.mozilla.org/en-US/firefox/addon/styl-us/
• https://brokkr.net/2025/02/04/web-browsing-in-2025-block-all-the-things/