This module comes with a default css stylesheet, which you can disable in the options. Files included for your convinence:

- views-acordion.css - A default stylesheet with how the classes the author thought would be best used.
- views-view-accordion.tpl.php - copy/paste into your theme directory - please the comments in this file for requirements/instructions.

Both files are commented to explain how things work. Do read them to speed things up.