Hey @ssmusoke,
After some good ‘poking’ on how to best customize bootstrap I would recommend @darius’ option c shared on this post
( c) leverage bootstrap-sass and rewrite the existing uicommons styles to use bootstrap’s mixins. This requires actual thinking, whereas the other two options are pretty brute-force.
It actually is the theming approach for bootsrap4 as stated in the documentation.
From the discussions that have been going on, I get the impression that the starting point of the integration is the Reference Application (please correct me if I am wrong). I’m having a bit of a challenge locating the ref app repo as my search returns 6 different repos.
cc: @dkayiwa