Hey Carlos,
Thanks for reaching out to us!
Unfortunately the Eventbrite ticket section there is an iFrame which posts it’s contents to your page from the Eventbrite website.
You can’t style the contents of an iframe using just CSS, you’ll need to using javascript to find the content and insert inline styles to change the way those elements display. You can see more about this in this Stack Exchange thread http://stackoverflow.com/questions/583753/using-css-to-affect-div-style-inside-iframe.
Let me know if this helps.
Thanks!