the problem seems to be that all pages do only reload. So there must be a setting in his installation that overrides the default behavior ( namely to redirect to the homepage ).

btw. even if you are opening a media query – but have some other media querries inside that open and close correctly – a following closing bracket then have no effect.

see here some code of your css ( those rules that are correct are erased here )

@media only screen and (max-width: 767px) {
	.responsive #top.page-id-472 .avia_responsive_table .avia-data-table tr:first-child th {
		display: block;
	}
} 
/**** closed too early ? ******/
	.responsive #top.page-id-472 div .avia_responsive_table .avia-data-table td, 
	.responsive #top.page-id-472 div .avia_responsive_table .avia-data-table th {
		padding: 0;
	}
} /**** or an additional superfluous bracket  ******/

@media only screen and (max-width: 767px) {
	#top .avia-icongrid.av-flex-cells.av-break-989 .av-icon-cell-item {
		flex: 1 1 100%;
	}

	.avia-icongrid-flipbox .av-icon-cell-item .avia-icongrid-front .avia-icongrid-inner, .avia-icongrid-flipbox .av-icon-cell-item .avia-icongrid-flipback .avia-icongrid-inner {
		padding: 0 3em;
	}

	.all_colors h3 {
		line-height: 1.3; /* Adjust the value to increase or decrease spacing */
	}

	.keinspace span {
		display: block; /* Ensure the span is treated as a block element */
		margin-top: 0px; /* Adjust margin-top to reduce space */
		font-size: 0.7em; /* Adjust the font size smaller */
		color: #6F6571; /* Change the text color to grey */
	}

	.avia-cookie-consent {
		width: 100%;
		position: fixed;
		background-color: #009BDD;
		z-index: 999;
		color: rgba(255,255,255,0.9);
		padding: 1.1em;
		text-align: center;
		opacity: 1;
		visibility: visible;
		transition: all 0.3s ease-in-out;
		overflow: hidden;
	}

	.avia-cookie-consent-button,
	.avia-cookie-info-btn,
	.avia-cookie-hide-notification,
	.avia-button {
		background-color: white !important;
		color: black !important;
	}

/**** missing closing curly bracket ******/

/***** some media querries inside here - that are correctly opend and close so the following closing has no effect to that before *******/

.av-burger-menu-main.menu-item-avia-special {
		display: block;
	}
}  /**** additional superfluous bracket  ******/

It is therefore best to avoid nesting media queries and possibly combine the same ones.
There are a lot of single @media only screen and (max-width: 767px) {

I would like to go to the start page by clicking on the logo.

this is standard behavior of Enfold setting ( WordPress on general). So if this is not the case there had to be something ( maybe allready in your functions.php) that hampers this action.

So what is exactly on your code in the XXXX part. Or just get rid of that entry. And have a look what happens then.

In the meantime, I prefer to have my custom SVGs in a folder: /wp-content/uploads/dynamic_avia/avia_custom_shapes
this is a default folder for custom svg dividers – but you have to create it yourself.
Now we just register the custom svg files – add this to your functions.php of the child theme:

function custom_avf_custom_svg_shapes( array $custom_shapes ) {
$custom_shapes = array(
	'tilt-with-shadow'	=> array(
		'key'			=> 'tilt-with-shadow',
		'title'			=> __( 'Tilt with Shadow', 'avia_framework' ),
		'has_width'		=> true,
		'has_flip'		=> true,
		'filename'		=> 'tilt-with-shadow'
		),
	);
return $custom_shapes;
}
add_filter( 'avf_custom_svg_shapes', 'custom_avf_custom_svg_shapes', 10, 1 );

this svg you can find at:
https://webers-testseite.de/wp-content/uploads/tilt-with-shadow.svg

if you click to the svg now : you can see the black fill of the svg – that is the trick on svg-dividers all path ( polygones, circles etc. ) that has no fill color in the svg get the color you set on the alb.

Result: https://webers-testseite.de/bg-video/

you tried to do it with slanted border – but try with svg separator instead and check the mark “bring to front”

https://webers-testseite.de/bg-video/

if i test my page on : https://securityheaders.com/?q=https%3A%2F%2Fwebers-webdesign.de&followRedirects=on

you can read the description of:

x-content-type-options: X-Content-Type-Options stops a browser from trying to MIME-sniff the content type and forces it to stick with the declared content-type. The only valid value for this header is “X-Content-Type-Options: nosniff”.

So your advice is to change the mime types for those generated post css to : text/css

but as far i can see on : class-post-css-management.php – line 919:
return '<style type="text/css">' . $this->new_ln . $rules . '</style>' . $this->new_ln;

isn’t this responsible for those css settings?

__________

i set the filter ( avf_post_css_create_file ) now on one of my testinstallations to true ( only then files are generated inside dynamic-avia folder) – and switched of merging.
On dev tools i checked if i find some text/html in DOM – but nothing to find.

and your layerslider got the id 8? and nomenklatura is there a bit different #layer_slider_X
on default the first on a page will have : #layer_slider_1
the next #layer_slider_2

so you can have:

@media only screen and (min-width: 768px) {
  #layer_slider_1{
    display: none!important;
  }
}

@media only screen and (max-width: 767px) {
  #layer_slider_2{
    display: none!important;
  }
}

check your page with developer tools which ID those sliders have.

_______

or you can have both videos in one layerslider and choose there the visibility.
you have on each layer on the right side the tabs of layersettings – and on content tab you can set the layervisibility for desktop, tablett, mobile “toggle device visibility”

i could not test it now if it works – but the code from : https://kriesi.at/support/topic/accordion-slider-stop-allowing-all-images-to-show-in-slider/#post-1435166 does not lead to a functions.php error on my end here – means – the syntax is o.k.

You could set the grouping manually, using custom classes in combination with scripts in functions.php; in general, however, it is sufficient to keep the corresponding elements within a color section. And then set a new section for the next element.
Unfortunately I can’t see your page to give better advice.

but: do not forget on avf_header_setting_filter_mod to add the class to header!
(preserve the a space on the first class that is added)

$header['header_class'] .= " av_header_transparency";

and conditional for search is : is_search( )

add_filter('avf_header_setting_filter', 'avf_header_setting_filter_mod', 9999, 1);
function avf_header_setting_filter_mod($header){
    if ( is_archive() || is_singular('post') || is_search() ) {
        $header['header_transparency'] = 'header_transparency';
        $header['header_class'] .= " av_header_transparency";
    }
    return $header;
}

No, not as the opposite, but in all corners. However, this property can also be intended for one corner each.

have you seen this :
(click to enlarge the image)

i do have this nearly on all my installations in the htaccess file:

<IfModule mod_headers.c>
Header set X-Frame-Options "sameorigin"
Header set Referrer-Policy "strict-origin-when-cross-origin"
Header set X-XSS-Protection "1; mode=block"
Header set X-Content-Type-Options "nosniff"
Header set Strict-Transport-Security "max-age=31536000; includeSubDomains; preload"
Header always set Content-Security-Policy "upgrade-insecure-requests"
Header always set Permissions-Policy "geolocation=(), midi=(),sync-xhr=(),accelerometer=(), gyroscope=(), magnetometer=(), camera=(), fullscreen=(self)"
</IfModule>

and had never such problems – but maybe you are right – it could be matter of inline css files. I do allway set this to my child-theme functions.php:

function custom_avf_post_css_create_file( $create ){
  return true;
}
add_filter( 'avf_post_css_create_file', 'custom_avf_post_css_create_file', 10, 1 );

yes – please excuse me for not explicitly mentioning this.

Again my question : you like to have on lightbox only your caption – or do you like to have a combination of title + caption or alt + caption ?
see: https://webers-testseite.de/images-with-caption/

The trick is to have an own lightbox behavior on that links.
In the script, I first tested preventing the original event with preventDefault. This sometimes worked – but sometimes not. I therefore set the noLightbox class for these links. This removes the class lightbox-added and I can then program a new behavior. Including a new markup (here, however, it is the standard markup).