Change the background color of PDF wrapper & adjust the gap size

Hello, I have implemented the Adobe Embed API with IN LINE view mode in our platform PDF Rendering. There are two questions I would ask:

1. How to change the background color of the PDF wrapper, as far as I know, the default background color is white, I need to change it to transparent or or adjust it to the background color on my website page.  I can't modify directly to the DOM element since it uses an iframe to render the PDF.

I have read the same topic here but it only works with older version SDK.

(see the attachments)

2. How do we change each page's gutter/gap size?

I don't see the option to change this in the documentation.

Anyone know how to achieve this?

Thank you.