Good evening Simon and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
I would love to help you with this topic.
First off, you are absolutely right, this is related to a CSS rule from your theme.
More specifically:
@media only screen and (min-width: 1200px) {
.cb-main {
width: 750px;
}
}
Note that this rule is likely to be found in several places in your CSS stylesheet (for the different widths).
There are couple of things you can do:
- Explore the page at different resolutions using https://theeventscalendar.com/knowledgebase/using-google-chrome-developer-tools/ to find out which rules cause issues
- Experiment with different Events -> Settings -> Display settings as described here: https://theeventscalendar.com/knowledgebase/stylesheets-and-page-templates/
If you decide to add CSS rules, try something like
.single-tribe_events #cb-content .cb-main {width: 100% !important}
Let me know if that helps.
Have a great day!
Geoff B.