Hi,
I build the Suite CRM for our internal use, Issue right now I am facing issue with its UI, not Theme.
Home Screen is totally blank.
Few people can see there Home and few are not.
Same issue with Activity, Not able to add Dashlet. As activity Tab is not Visible.
You probably have nor set file ownerships and permissions correctly, and your CRM is crashing (thus showing a white screen).
Make sure you follow the instructions on the installation guide, and that you determined your web server user correctly (otherwise the file ownership will not be correct)
https://docs.suitecrm.com/admin/installation-guide/downloading--installing/