Hello @Jayron_Rosel ,
Using a Plug-in?
Are you using a Plug-in or customization on your Kintone Calendar App?
For example, are you using the KDDI's Calendar Plus Plug-in or Calendar Ver. 1.6.0 Native Kintone Plug-in?
If you are using the KDDI’s Calendar Plus Plug-in, then (as mentioned before), you should contact the KDDI America team for support .
You are welcome to keep asking questions about building customizations or Kintone Native Plug-ins!
However, we do not provide support for 3rd party Plug-ins.
Not using a Plug-in?
If you are not using a Plug-in, creating a custom Calendar View using Custom view may be a good option.
This way, you can set up your own styling (CSS) to fit your exact needs.
Here are references to get you started:
A drag & drop event calendar (for Javascript) that is fully responsive and compatible with all modern browsers.