Im not sure what version of the article templates you're using, but if it works right now then no need to touch any of the article templates
just install the new magnum theme and then copy paste colors from your old version to new version, simple
But seriously, updating the article templates is just a couple of clicks xD, go to ACP > Pages > Templates > and delete any template name that starts with S1 for example S1 One Column
Also delete a different article styles plugin, and then do a complete reinstall which is two clicks, 1, re-upload the templates. 2, install the plugin
thats all