My theme is overriding WP Post Popup styling

Hi,

I am trying to get WP Post Popup to work with Onepress theme. I created a modal link as described in documentation. I’m using default WP Post Popup settings. However, when I click on the created link on my website, the article I linked to is displayed on top of everything with no styling whatsoever – without even the white background box, just plain text on top of my page.

I suspect that my theme is overriding the WP Post Popup styling, but I am not sure how to change the priority of the styling. Or perhaps this is something else entirely. Can you please take a look at my link, and tell me what’s wrong? To view the page without the modal link, remove everything after “?” mark (“?” included). The scroll down a little, and look for big handshake icon, and a link named “Sužinoti daugiau”. That’s the modal link.

Please let me know how I can fix this ASAP. Thank you!

The page I need help with: [log in to see the link]