Make "disable feature" toggle more obvious/intuitive

While testing the JSF UI customization acceptance criteria for Branding, it was not at all clear how to switch back to the default branding without creating a separate branding named "default":

Original acceptance criteria:

• Select a logo (by uploading it to resources, not taking one that is already there).
• Set a grey header, black footer, set links colors to yellow, go to Login Page tab and select a login background video (ex: http://mirrors.standaloneinstaller.com/video-sample/video-sample.webm , MIME Type: video/webm ).
• Check Set as default branding.
• Deploy.
  • Logo is correctly applied
  • Grey header
  • Black footer
  • Yellow links
  • Login background video
• Put back branding default values.
• Deploy.

After a thorough search of the documentation, I only found this in the branding doc, which doesn't seem to exist anymore:

If you don't want to use your branding during a test you can disable your default branding without deleting it.
Just tick the Disable theme branding option above the tabs. The tabs and their content will be displayed under a gray overlay.