The following are required for developing Kintone plug-ins.
Development Environment for Kintone Customizations
See Get a Developer License for more details on obtaining a free Kintone developer license.
Environment to Run the Packaging Tool
An environment to run the shell script that is introduced in the below Plug-in Examples section is necessary. For those working on a Windows environment, a tool such as cygwin can be used to run the script.
A collection of plug-in examples that contains the packaging tool, CSS file, README, and samples can be downloaded from the following Github link.
Check the below link for instructions on how to utilize the plug-in CSS file.