Thank you for your reply and code for functions!
Regarding slider – I modified mobile screen view with css by decreasing font size and margin between titles and buttons. Works for now for usand does not too much space for the image (853px height would be too much for us)

Thank you, your advice regarding the mobile menu helped me to solve the issue!
Unfortunately, if I add a bigger image for the slider (I tried same then in event star demo has: 1280×610), it will display too high image on the desktop, all feature information section will be out of the viewport but mobile version is still a bit out of proportion and slider buttons are also out of the view partly. What would be the perfect dimension for the slider from theme perspective? And would it be possible to set a mobile version slider size in css?

Is there any news about the issue? I really need now to go live with the short url..

While site home url is changed also customizer does not work, I managed to get there fatal error that something is wrong in file event star – class-at-theme.info.php
in row 63. I tested that row in php validator, there were no errors according to that. However, only option to get site back was to deactivate event star theme, change urls back and deactivate troubleshooting plugin I was using to test.
Also – if the site`s home url is different, also admin bar disappears when I´m in a page view. I have another site (with other themes) set up like that and there is no errors like that. Any response from author would be much appreciated!

I switched off all plugins one by one, same problem appeared every time.
Child theme is done according WordPress.org descriptions (https://developer.wordpress.org/themes/advanced-topics/child-themes/).
My functions.php file is following:
<?php
function my_theme_enqueue_styles() {

$parent_style = ‘event-star-style’; // This is ‘evemt-star-style’ theme

wp_enqueue_style( $parent_style, get_template_directory_uri() . ‘/style.css’ );
wp_enqueue_style( ‘child-style’,
get_stylesheet_directory_uri() . ‘/style.css’,
array( $parent_style ),
wp_get_theme()->get(‘Version’)
);
}
add_action( ‘wp_enqueue_scripts’, ‘my_theme_enqueue_styles’ );
remove_filter(‘widget_text_content’, ‘wpautop’);
?>

I realised menu is working for 768px screen size if I remove that last part:
add_action( ‘wp_enqueue_scripts’, ‘my_theme_enqueue_styles’ );
remove_filter(‘widget_text_content’, ‘wpautop’);
But then all thedesign is messed up.