Facebook messenger appears behind content

Hey Jordan, thanks for reaching out.
It disappeared as soon as I enabled the enfold cookie banner.
In a different topic on this forum I saw that another moderator recommended
placing the Facebook messenger chatfunction in the functions.php page.
So I put it below everything within a custom script tag.

Hai Jordan, yes I would like some help.

I deleted the facebook code and accidently also something important.
I now have an errorcode

Uncaught Error: Call to undefined function avia_get_header_scroll_offset() in wp-content/themes/enfold/css/dynamic-css.php:1005
Stack trace:
#0 wp-content/themes/enfold/includes/admin/register-dynamic-styles.php(159): require()
#1 wp-content/themes/enfold/functions.php(689): avia_prepare_dynamic_styles()
#2 wp-includes/class-wp-hook.php(287): avia_custom_styles(”)
#3 wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters(NULL, Array)
#4 wp-includes/plugin.php(478): WP_Hook->do_action(Array)
#5 wp-settings.php(540): do_action(‘init’)
#6 wp-config.php(90): require_once(‘/mnt/web013/d0/…’)
#7 /mnt/web013/d0/42/57402342/htdocs/WordPress_

What I tried to do, was delete and then again add the facebook messenger code.
It’s still does not appear and also I would like the mobile menu to be sticky.
I tried adding the code as I found it on this forum but I accidently deleted to much I believe.
Can you help me add the facebook messenger code and the sticky mobile menu.

Thank you Victoria,
So for clarity:
I edited the functions.php, First I added the script tags and within them the facebook code for messenger chat function.
Then I enabled the Enfold Cookiebar. This made the facebook messenger chat function disappear.
So I tried readding it and also adding the sticky mobile code I found on this forum.
This didn’t work. So I deleted the codes I added in the functions.php but I accidently deleted too much
and now I have an errorcode. What I want is the facebookmessenger code and the sticky mobile menu since my website is mostly viewed via mobile.

Thanks for the help, I appreciate it

Uncaught Error: Call to undefined function avia_get_header_scroll_offset() in wp-content/themes/enfold/css/dynamic-css.php:1005
Stack trace:
#0 wp-content/themes/enfold/includes/admin/register-dynamic-styles.php(159): require()
#1 wp-content/themes/enfold/functions.php(689): avia_prepare_dynamic_styles()
#2 wp-includes/class-wp-hook.php(287): avia_custom_styles(”)
#3 wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters(NULL, Array)
#4 wp-includes/plugin.php(478): WP_Hook->do_action(Array)
#5 wp-settings.php(540): do_action(‘init’)
#6 wp-config.php(90): require_once(‘/mnt/web013/d0/…’)
#7 /mnt/web013/d0/42/57402342/htdocs/WordPress_