Hi Pavel,
Thanks for reaching out.
It seems that the issue is in your contact page, and it shows only one menu item in the Navigation bar. A few illegal characters and an external file inclusion have been also found through the browser debugger.
I would suggest you troubleshoot the page and remove the character and include an external CSS file in a WordPress standard. Please find the article here on how to add a CSS file to the WordPress: https://www.wpbeginner.com/wp-tutorials/how-to-properly-add-javascripts-and-styles-in-wordpress/
If you get the same issue after following the above process, please let us know for further investigation.
Please remember that we don’t offer any support or investigation on the issues related to the custom codes.
Thanks