CSS: m.facebook.com - cleaner UI

This script adjusts UI of m.facebook.com to get rid of useless panels:
- MBackNavBar - back arrow header above the current message - is removed
- MStoriesTray - box with various stories - is removed
- conversation guides are removed
- clickable area around "Like", "Reply" and "More" is made smaller to solve click problem in mobile Mozilla Fenix

Please try another script for m.facebook.com, which enables text copying in mobile browsers: https://gf.zukizuki.org/en/scripts/419355