Hi Shea,
Yeah, there are a ton of wrappers on that iframe object, so it can be tough to override the width without it being overwritten by the width of another parent element.
This seemed to do the trick when I was scoping out the site using DevTools:
.eventbrite-iframe {
width: 96% !important;
}
That should work given that it is the very top element in the cascade, even above the iframe itself. And, since all other widths are percentages, this will base all the other widths on this 96%.
Let me know if that works. 🙂
Cheers!
Geoff