The placeholder is an image generated by a third party service and it doesn't have font size control. You can customize the placeholder if you set the package to use it as a backup ad and change it manually from the ad list.
Added a new AdBlock detection option to display a dismissible notice. The notice can be styled via style properties.
Added support for Social Gorups add-on for main content template ad positions.
Ad saving issue when trying to remove XF template syntax from the ad code.
@I. C. Daniel, It depends on your site and the display of the device. The wider the main content, the less space available for background image. The image fits the background so you can start with 1920 x 1200 and see how that looks on different devices.
What you can do currently is to restrict room access based on user group. The "Default joined rooms" chat admin option works with the room permissions so you can select any room and will join user based on user group permission.