By default, the single event page template will try to find your website theme’s header and footer and create a page. If the page is missing styles or has any layout issues, you will want to copy the event detail template to your theme folder and customize it to match your page.php or single.php template.
Copy the template view file from the plugin folder
Look for megacal-event-detail.php at yoursite.com/plugins/megabase-calendar/view/
Duplicate this file to your local theme
Create the megabase-calendar folder and views subfolder in your theme as shown.
Save a copy of megacal-event-detail.php to this views folder.
Modify the view template file as needed
Edit the file as needed to add custom wrapping markup and classes etc.
For example, your theme might have wrapper divs with classnames like this theme we assisted a client on: