If you view a Joomla site that uses the default Bootstrap CSS provided by Joomla, it may appear broken in Safari 15 or earlier on macOS. On large screens, instead of grids, the page might display as if it's being viewed on an extra-small (XS) or mobile-sized device, with grid layouts missing.
To resolve this issue, replace the contents of the Joomla `media/vendor/bootstrap/css` folder with files from the official Bootstrap website:
https://getbootstrap.com/docs/5.3/getting-started/download/
Joomla version 6.0.3 includes Bootstrap 5.3.8.
For testing on older versions of Safari and macOS, you can use a service such as:
https://accounts.lambdatest.com/