you are working with a child-theme – but have no functions.php in there?
The downloadable preset child-theme of Enfold has it on default: https://kriesi.at/documentation/enfold/child-theme/

And this is all what is in the starting child-theme functions.php

<?php

/*
* Add your own functions here. You can also copy some of the theme functions into this file. 
* WordPress will use those functions instead of the original functions then.
*/

for the second request – look into your source code and see what ID the first image got- on that page above it is : #av-masonry-1-item-125

function start_with_clicked_state(){
?>
<script>
(function($) {
$(window).load(function() {
    setTimeout(function() {
        $('#av-masonry-1-item-125').trigger('click'); 
     }, 1000);
 });
})(jQuery);
</script>
<?php
}
add_action('wp_footer', 'start_with_clicked_state');

see here my example page: https://webers-testseite.de/gallery/
with both codes above : after 1sec the lightbox starts – every 6sec the image will load the next one.

so you do not have to do something on the starting page: http://fvs.768.myftpupload.com/kitchens/
just see the ID of the first image you have on that newly opend one (http://fvs.768.myftpupload.com/before-after-stained-kitchen-cabinets/)

this is better:
try this in child-theme functions.php:

function set_interval_for_lightbox(){
?>
<script>
(function($) {
setInterval(function() {
	if(typeof($.magnificPopup.instance) != 'undefined') {
		$.magnificPopup.instance.next();
	}
}, 6000);
})(jQuery);
</script>
<?php
}
add_action('wp_footer', 'set_interval_for_lightbox');

6000 is the interval in milliseconds

but i do not know (yet) how to link directly from the one gallery to a “lightbox gallery slideshow” on the other page.
The code above will work on every sub-page like: http://fvs.768.myftpupload.com/before-after-stained-kitchen-cabinets/

you can add the link definition as it is presented at google fonts to the head section by child-theme functions.php via:

add_action('wp_head', function() {
?>
  <link href='https://fonts.googleapis.com/css?family=Amatic+SC&display=swap' rel='stylesheet' type='text/css'>
<?php
});

PS: on GDPR (DSGVO) Reasons – i load the font localy – and this works good

https://kriesi.at/support/topic/enfold-image-sizes-3/#post-1109028

or let some in but redefine the width and height of them:

function custom_modified_thumb_sizes( $size ){
  $size['square'] = array('width'=>300, 'height'=>300 );      
  return $size;
}
add_filter('avf_modify_thumb_size', 'custom_modified_thumb_sizes', 10, 1 );

to set the crop behavior that line looks this way:
array('width'=>300, 'height'=>300 , 'crop' => false);

well ok that it is solved . But your layout is unique in the source code –
you got color-section | 1/1 container | color-section | 1/1 container
these 1/1 container have on default wrapping parent containers which have on default border-top.
The 1/1 container Border is something different.
If you do them all in color-sections you can influence that behavior – or with the code above delete the default behavior. ;)

• This reply was modified 6 years, 4 months ago by Guenni007.

this is not a border – it is a box-shadow:

.av_minimal_header_shadow {
    box-shadow: none !important
}

but maybe you decide to have it on scrolled state – then only use this in your quick css:

.av_minimal_header_shadow:not(.header-scrolled) {
    box-shadow: none !important;
}

In my opinion, the above is indeed relevant. Because to prevent the automatic generation of the image sizes you have to set this.
Your question is first about how you can delete the generated alternative images. I think, if you e.g. use this “force regenerate thumbnail” and have used that code before, the files that are no longer needed will be deleted.
There shouldn’t be any performance reasons when using a CDN, only memory space savings are achieved.

is it intentional that the hamburger menu is also hidden?

you got that intention to have the mobile menu break at 1320px but the display none of

nav.main_menu {
    display: none !important;
}

hides the hamburger too:
try this instead:

@media only screen and (max-width: 1320px) {
#avia-menu {
  display: none !important;
}
#advanced_menu_toggle, #advanced_menu_hide {
  display:block !important;
}
}

i do not know why then the hamburger is centered because on default the mobile hamburger icon goes to the right:
https://kriesi.at/themes/enfold-medical/

that product table is placed in what kind of container?
if it is in a color-section – i would give that color-section a unique-ID (as mentioned above – to better select that table)
and that to quick css:

.responsive #custom-ID .container {
   max-width: 1810px;
}

just replace #custom-ID with the ID you gave to your color-section.
thats it.

there is no event at the input field – so maybe the script isn’t loaded.
What do you have on Enfold (Child) – Performance ? : “Disabling of template builder elements” load all – only used or manually.
Maybe a refreshing of the merged files will do the change.

on enfold (child) – Blog Layout – you got this: “Single Post Navigation”

if you only want to remove it :

Select to disable or enable the post navigation that links to the next/previous post on single entries. Setting is also used for portfolio. Use filter avf_post_nav_settings to customize.

maybe this function can help you – but after that you had to regenerate image files – there are a lot of those tools – i guess the force regenerate thumbnails is the one which removes unneeded files too.
the first function is for not to use a srcset for images

// remove "responsive images" functionality in WP 4.4 and higher
add_filter('wp_get_attachment_image_attributes', function($attr) {
   if (isset($attr['sizes'])) unset($attr['sizes']);
   if (isset($attr['srcset'])) unset($attr['srcset']);
   return $attr;
}, PHP_INT_MAX);
add_filter('wp_calculate_image_sizes', '__return_false', PHP_INT_MAX);
add_filter('wp_calculate_image_srcset', '__return_false', PHP_INT_MAX);
remove_filter('the_content', 'wp_make_content_images_responsive');

// Disable loads of Enfold & WP image sizes upon upload
// do image sizes manually, double-size with high compression for retina screens
// use Photoshop to set exact double size and quality between Q30 and Q40
add_action('init', 'remove_enfold_image_sizes');
function remove_enfold_image_sizes() {
// do NOT remove widget size, is used in backend portfolio items!
// remove_image_size('widget');
  remove_image_size('square');
  remove_image_size('featured');
  remove_image_size('featured_large');
  remove_image_size('portfolio');
  remove_image_size('portfolio_small');
  remove_image_size('gallery');
  remove_image_size('magazine');
  remove_image_size('masonry');
  remove_image_size('entry_without_sidebar');
  remove_image_size('entry_with_sidebar');
  remove_image_size('shop_thumbnail');
  remove_image_size('shop_catalog');
  remove_image_size('shop_single'); 
    remove_image_size('shop_gallery_thumbnail');
}
// Remove unneeded WP image sizes
add_filter( 'intermediate_image_sizes_advanced', 'prefix_remove_default_images' );
// Remove default image sizes here. 
function prefix_remove_default_images( $sizes ) {
// do NOT remove small and medium sizes, they are used in backend Media Library!
// unset( $sizes['small']); // 150px
// unset( $sizes['medium']); // 300px
 unset( $sizes['large']); // 1024px
 unset( $sizes['medium_large']); // 768px
 return $sizes;
}

test it on a testinstallation. I tested it on a wordpress playground with enfold installation without any conflict.
All Credits goes to: https://kriesi.at/support/topic/responsive-content-images-retina-screens/#post-1077293

look to functions.php of your enfold theme (parent) around line 148ff
here without the comments in it:

$avia_config['imgSize']['widget'] 	= array('width'=>36,  'height'=>36);
$avia_config['imgSize']['square'] 	= array('width'=>180, 'height'=>180);
$avia_config['imgSize']['featured'] = array('width'=>1500, 'height'=>430 );
$avia_config['imgSize']['featured_large'] = array('width'=>1500, 'height'=>630 );
$avia_config['imgSize']['extra_large'] 	= array('width'=>1500, 'height'=>1500 , 'crop' => false);
$avia_config['imgSize']['portfolio'] 	= array('width'=>495, 'height'=>400 );
$avia_config['imgSize']['portfolio_small'] = array('width'=>260, 'height'=>185 );
$avia_config['imgSize']['gallery'] = array('width'=>845, 'height'=>684 );
$avia_config['imgSize']['magazine'] = array('width'=>710, 'height'=>375 );
$avia_config['imgSize']['masonry'] = array('width'=>705, 'height'=>705 , 'crop' => false);
$avia_config['imgSize']['entry_with_sidebar'] = array('width'=>845, 'height'=>321);
$avia_config['imgSize']['entry_without_sidebar'] = array('width'=>1210, 'height'=>423 );
$avia_config['imgSize'] = apply_filters('avf_modify_thumb_size', $avia_config['imgSize']);

filter avf_modify_thumb_size – how to use it ?
e.g:

function custom_modified_thumb_sizes( $size ){
  $size['square'] = array('width'=>300, 'height'=>300 );      
  return $size;
}
add_filter('avf_modify_thumb_size', 'custom_modified_thumb_sizes', 10, 1 );