Hello, @antongschaffer,
Thanks for the explanation. The thing is if you try to set/change the theme settings it will apply to the entire site. But as you stated you want to change the container for only 1 page and for desktop only. For this, you can use custom CSS code.
To address this issue, please follow these steps:
Navigate to the Dashboard.
Proceed to “Porto.”
Access “Theme options.”
Select “Skins.”
Choose “Custom CSS.”
Paste the provided code at the bottom of the black box.
Save the settings.
To view the changes on your site, clear your browser cache and revisit your website.
@media(min-width:1320px){.single-event .container{max-width:1300px !important;}}
Note: In the above code the word 1300 is the width you can change it with the size you want.
Best Regards,
PThemes Team.