Hi,
I tested the webpage, the text column is fixed when scrolling. But the version(on expo-still.nl) is not new. This part of the codes was updated.
Please try to upgrade both the SEA theme and BM Content builder plugin(how: https://doc.seatheme.net/sea/installation/how-to-update-sea-theme-and-plugin/). The update will not remove existed posts/pages/portfolios/options. But I still suggest you make a backup before the update.
Regards!
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