First of all, Thanks for the screenshots of your issue to understand it better.
I have checked your issue on your site and fixed it by using a custom CSS code. I added custom CSS code in the PORTO >> Theme Options >> Skins >> Custom CSS >> at the bottom of the black box.
Please first check the images I attached in the private content area of this topic and then check back to your site after clearing the browser cache.
Have a nice day.
Best Regards, PThemes Team.