There used to the option to preview the client area. One was after clicking save on the customising the client area page, as descript here:
Where can I see my changes?
Any of the settings configured here will be adopted by the client area instantly on save. When you save your changes you will see a link which will pop open a new preview window.
…and one used to be on the client page inside the contact field, as descript here:
You can also Impersonate any of your saved clients from the respective client detail screen. This will allow you to simulate their experience when they access your client area. The client area will only be accessible for those clients who have a saved contact, I.e. contact name and e-mail.
But both option are gone on my account or do I miss something?
That is how it looks on my account: