Hi Kristian,
Lets cover these issues one at a time:
One: To change the background color of the Hover State, you will need to change the background-color hex code for that CSS style:
Add this to your Eventon Style Settings in backend and change the #f4f4f4 to whatever you want:
.eventon_events_list .eventon_list_event a.desc_trig:hover { background-color:#f4f4f4 !important; }
For your second issue: The eventon plugin is set to be 100% of the DIV that is resides inside of, I checked your page, and it seems that the page does not have a DIV that has any widths, it is just displaying inside the main page which is giving Eventon 100% of entire page width.
You will need to set a Page width to fix your issue.
If you need help, let me know.
or simply