On Voice for new sites we are only offering Bootstrap and Modern themes as standard, as the other old themes are not responsive and don't look good on mobile/tablet screens.

My general advice would be to use one of these themes with your site, and customise it using the various theme settings availalbe, and adding in your own extra css on top of this in the theme options if you wish to.

If you really want the old "use custom stylesheet" theme then I can make it available to your site - though then it'll be up to you to ensure it works corrrectly on different screen sizes etc.

Thanks

Joe - Voice Admin