How to add left margin to single event page

The calendar page looks great. But on the event description page there is no left margin and the text bumps up against the edge of the content box. If I choose any template (such as one of my theme’s templates) other than the default events template, the event page improves, but the calendar page breaks completely. Only code shows.

I just want to add left margin to the single events page. I’m kinda surprised this isn’t built-in or a setting.

I tried creating a tribe-events.css file where I have this definition: .single-tribe_events {
margin-left:15px;
}
And I uploaded that into a tribe-events folder inside my theme folder. No effect.

What now?

https://wordpress.org/plugins/the-events-calendar/