This site is currently running the trunk development version of Tiki Wiki CMS Groupware, which will be Tiki 19 when it's released in October. For this version, Bootstrap 3 has been updated to Bootstrap 4. That means there are many changes to make in Tiki's files to maintain compatibility with this latest Bootstrap CSS framework version. In particular, not all of the visual themes at this site have been updated yet, so if you select a theme that seems broken or has elements that don't seem quite right, it's one of those that need updating, and it will be fixed before long.