Buttons and Form elements have a top level class (style) and are expanded to differing styles through the use of combo classes. Edit the top level class first to define common styles.
There are four pre-set button classes available. The baseline .button class is where the designer should make common button style decisions, and then define specific variants based off this through combo classes (.is--light etc.) The designer is encouraged to create further variants as needed following the same process.
Forms, form fields, and form text areas can be edited below. Specific form field styling should be defined on the baseline .c-text-input class (height, hover state, corner radius etc.), with edits to the .is--text-area combo to define more specific style choices, such as height.