Custom CSS - Overlay Header Onto a Block

I am looking to add 4K video to the background of my home page...is there custom css which would allow me to add a "bring to front" function to the header? I hope to overlay the header onto a video block so that my video can extend to the top of the webpage and appear behind buttons and titles.

Can you share your website URL and the page this is on?

https://www.jupiternarrowsconservation.org/

Password:   JNCA

The video is on the homepage, currently playing back at a resolution of 1920 x 1080 because it is the background of a block. 

My hope is to create a video block so that the video can play back at full res (4K) and extend the video block to the full dimensions of the page like the current video does. However, after messaging with customer support, I was informed that there is currently no way for headers to be overlayed on blocks like this.

Thanks for your help!

1 hour ago, SUEJNCA said:

My hope is to create a video block so that the video can play back at full res (4K) and extend the video block to the full dimensions of the page like the current video does. However, after messaging with customer support, I was informed that there is currently no way for headers to be overlayed on blocks like this.

Can you set the page up with a video in a block and extended to the edges and then share that page here? I can give you CSS to then put the section behind the header.

Thanks, I added a block and extended it to the edges of the page. The URL is the same...

www.jupiternarrowsconservation.org

password:  JNCA

As far as I can tell the page is the same with a background video not a video block.