Hello Maratopia,
Thanks for writing in!
Please be advised that this icon:

is a link to the live view of the page. This is a not an export a page or something. The reason why your page does not have the custom CSS applied to it is because of caching. I can see that you have installed HummingBird plugin. Before viewing or testing your page, you will NEED to always clear the plugin caches so that the latest saved version will be displayed and not the cached one. At this moment, since you are still building and editing the pages, temporarily deactivate your HummingBird plugin and any other optimizing plugins (if you have installed any). They are best to turn ON when you are done building the site and ready to go live.
If nothing is helping, provide us access to your site so that we can check your settings. Please create a secure note with the following info:
– Link to your site
– WordPress Admin username / password
To know how to create a secure note, please check this out: https://theme.co/docs/getting-support
Best Regards.