Updating your Plone theme to Diazo will allow it to be used beyond Plone 5...
Many fundamental theming methods must be mastered for creating themes that maintain full control over the display of Plone elements and content...
The combination of Lineage and LinguaPlone offers the ability to customize the look and feel of subsites, yet still update, manage and localize their content as part of the main site.
Some suggestions to help your Plone theme follow best practices
The next version of Plone is now in the Release Candidate stage and will be officially available in the coming months. I have been working with Plone 4 through the beta stages, but it wasn't until recently that I got to work with the new version as if I were implementing a design for a client...