
It is possible to keep the look for the old issues and at the same time to have a different look for newer issues. There are a few steps you have to take:
Create the new templates in a separate directory
Go to the Issue Configure screen and select the new issue, section and article templates for the issue (e.g. /new/issue.tpl, /new/section.tpl and /new/article.tpl).
Within your templates, make sure to create links to issue, section and article templates by using "uri" (see "Displaying the URL" in "Template Language Reference" chapter) instead of manually writing the link content. In other words, do this:
<a href="{{ uri }}">link</a>