Hello, can someone tell me how I can put my site offline so that visitors can only see a holding page, and that I can continue to develop the site?

I have enabled 'Coming Soon' but this seems to prevent me from editing any pages or at the least seeing my edits. I have tried to set site to offline in Global System Settings, but this appears to no longer functipon with Heliix installed/in use.

Once I login it just hides the login boxes but I see nothing different other than this.

TIA