Since WebCenter 12.1, it is much easier to do basic/ advanced customizations, using the WebCenter User Interface.
WebCenter only saves one customization at a time. After you modify an existing theme or create an entirely new customization, the previous look will be lost. However, there is a way to store your customizations and apply them again with a single click, by saving them as Themes. Using this functionality, you can easily switch between a set of different looks, whenever you like.
Procedure
All information concerning customizations can be found on help.esko.com, in the Customization Manual.
Start customizing WebCenter according to your needs by going to Admin > Preferences > Customizations.
When you are satisfied with your work, make sure to save your customization.
Connect to your WebCenter Web Server and browse to Drive:..\WebCenter\WebServer\tomcat\webapps\WebCenter_Inst\custom.
Warning
Customizations are done per WebCenter Instance, please make note of which WebCenter instance you are customizing and/ or creating a new custom Theme.
click to enlarge
Move the contents of your custom folder to a new folder on Drive:..\WebCenter\WebServer\tomcat\webapps\WebCenter_Inst\custom_templates:
The name used for your folder, will also be the name for your theme displayed in WebCenter.
Optionally, you can also add a small image named thumbnail.png in the root of your new theme's customization folder (recommended dimensions: 80 by 80 pixels).
Sky is the limit
Warning
Every change you make to your Customization Template (via the WebCenter Interface when you deploy the Custom Theme), is saved to the custom folder on your Web Server, in the corresponding Web Server Instance.
To update your Customization Template, copy the content of the custom folder and paste it in your Customization Template's folder.