Lets do the upgrade before adjusting CSS.
Install the latest cMap as a plugin and activate it.
Go to the Connections : Templates admin page and activate the default template.
Now you should be able to delete the old cMap and after you do, the new one will automagically show up.
Lastly, activate the new cMap.
If they are still CSS issues, come back and share a link to your directory and I’ll take a look.