This back-end OFBiz theme is bootstrap based and offers 4 colour variants. As an example
For more information about this component visit the product page in the OFBiz WIKI, which can be found at https://cwiki.apache.org/confluence/display/OFBIZ/Rainbowstone
JIRA issues related to this component can be found at https://issues.apache.org/jira/browse/OFBIZ/component/12313460
Committed revisions can be viewed at https://svn.apache.org/viewvc/ofbiz/trunk/themes/rainbowstone/