The CMS Design System follows the 2% rule: we officially support any browser above 2% usage and the last 2 browsers versions for each browser as observed by analytics.usa.gov. Currently, the latest 2 versions of Chrome, Firefox, Safari, and Edge are supported.
The CMSDS is designed to be compatible with different operating systems and browser versions in order to provide a broad range of support. Progressive enhancement and graceful degredation methodologies are used to accomplish this.
The CMS Design System is a living project that is constantly evolving. As such, we do not provide long term support for any version of the CMSDS outside of the latest major version. We recommend that you update your project to the latest version of the CMSDS as soon as possible after a new major release to ensure that you are using the latest features and bug fixes.