styles/prosilver/theme/stylesheet.css
are the crc32 values of the underlying CSS files. These get updated during the phpBB build process so that CSS changes can be detected by end-user browsers when an update has been made. It would appear that this didn't happen in the 3.3.11 build.
After updating some of my boards to 3.3.11 I noticed that an awaited fix didn't appear to have been resolved, specifically
My workaround was to manually update the hash values inMarc wrote: Sun Oct 22, 2023 2:09 pm Release highlights
- Notable Improvements
- Ensure compatibility of message editor layout with latest Safari: PHPBB3-17125
styles/prosilver/theme/stylesheet.css
and then purge the board cache in ACP so that browsers would recognize the CSS changes made in 3.3.11.