LoginSecure Slideshow: How to remove the white background color?
Inside the "Styling Tab" you can find under Extension Styling the option Background Color. This option will set the background color of the entire extension. By setting this option you can remove this white background.
Why is it white by default?
To be honest it never was set as white. It was not set at all and therefore it adheres to default CSS styling for HTML elements and that is 'transparent'. It is recommended to set a color that works well with the colors of the text in your slide overlay. This will create a good fallback. Example: Black background with Black text is bad while Black background with White text is great as fallback color.
KB Article: https://loginsecure.eu/helpdesk/knowledgebase/view-article/70-loginsecure-slideshow-how-to-remove-the-white-background-color