How to create flexslider slideshow as a background in drupal 8? My slideshow is working but it is not in the background -- I am using paragraphs that I thought would make it easier for my client to add new images - the "flexslider" is in the header and I did create a twig template to put it in the background - "paragraph-frontage-flexslider.html.twig" ; the "flexslider" is there but not in the background (I modified a slideshow background twig that I found) 

[section class="region-header.outer-wrapper" style="background-image: URL('{{file_URL(content.field_background_flexslider_imag['#items'].entity.uri.value)}}');"]
  [div class="overlay"][/div]
  [article]
    {{content.field_background_flex_caption}}
  [/article]
[/section]


Any help would be most appreciated!
Flexslider is a javascript library that makes a bunch of changes to the markup once it is loaded.  Instead of trying to put the images in as background images I suggest using position: absolute on either the flexslider itself, or the items you want to sit on top of it.

You may also need a z-index on some items to bring the to the front or send them to the back.