This is a follow-up of bug 122241 but for KDE5. Problem: Persona theme is not applied to the menubar
IIUC, this ticket in its current form is obsolete, since Personas are no more. The feature was removed in commit e1e9e2aa16f08a8fd9e38db706d63e8eceeda8d1 Author: Muhammet Kara Date: Wed May 22 22:25:37 2019 +0300 Kill Mozilla personas -> Closing as WONTFIX. Note however, there's currently a GSoC project to allow setting custom theme colors which should make customizing colors work once it's done. Pending WIP patch for the Qt-based VCL plugins: https://gerrit.libreoffice.org/c/core/+/168901