Priority

Primary actions should represent moving forward or have the highest priority (e.g. submit, save, add). Secondary actions represent moving backwards or lower priority than primary actions (e.g. back, cancel). Buttons with a primary action should always be on the right and use the class "smss-btn--primary".

DO
Cancel Submit
DON'T
Submit Cancel
Submit Cancel
Cancel Submit
Button Groups

Use smss-btn-group to group together buttons with related actions.

Examples
Show Hide
Button Placement

The placement of buttons on a screen depends on the button's purpose: