Hi Robert,
You’ll likely need to adjust a lot of the styles and it’s impossible to say specifically which ones. You’ll need to play around a bit adjusting various styles and testing them out in various resolutions. You could go off of the events.css stylesheet for some examples of what to restyle or you could create your own rules as needed.
Using Firebug or Chrome/Safari Webkit Inspector will make this job much easier as they allow you to inspect elements on a page and modify values live on the page. I would recommend playing around a bit with that and finding some styles that you’ll need to change and then copying those back into your stylesheet.
Your theme must have a media queries stylesheet where specific styles for different devices and resolutions are placed. You’ll want to figure out what to change for the Events Calendar and place styles in those media queries for the appropriate resolution.
I hope that helps.
Regards,
Jonah