Hi,
hard to say because :
1) JCalPro have different themes - so it could be also fault of JCal theme.
2) JCalPro is commercial product with it's own support - so if we don't buy it we can not check.
3) You didn't add URL - so How can I check it ?
Maybe you can use Firebug tool (addon for Firefox) to check which class you have to override ?
How to use this tool you can check here:
https://www.gavick.com/documentation/jo ... -size-etc/or on several movies on youtube.