DO NOT EDIT THE SYSTEM THEME!
This could cause problems with Settings and Event Administration.
Please copy the default theme and modify the copy to create your own themes.
NOTE! It is highly recommend to copy the default theme and give the copy a new name. Then edit that new theme instead of default. You can then select the new theme in settings. If you do not do this and then upgrade the calendar, it's possible that you will overwrite your modified default theme and will lose your changes.
To customize the calendar including table sizes, colors, fonts, graphics, etc., edit the esstyle.css file for the theme that you are using. If unfamiliar with editing CSS files, there are many free CSS editors and tutorials to be found on the web.
There is a "fan site" with some useful information, including CSS maps of the different terms (not an official Easy PHP Calendar web site): EPCTutorials.
You can also adjust the cell spacing, cell padding, the size of pop-up windows and more in Settings.
Rename the headerCustom.inc.php.new to headerCustom.inc.php and edit it to include your own information into Settings or the Event Manager. This is a PHP file, so you can also add program code if needed.