Border width, styles and radii for bounding elements.
Borders should use the standard width and this should be the default option when in doubt. Interactive elements, such as form inputs, may use the heavy option to visually set it apart, e.g. input errors. Heavier is reserved for active context indicators, such as disclosure and tabs.
Radii should be used on all corners of bounding elements. Brands can set this to 0 to remove all border radius.