Button groups are used to bunch together buttons with similar actions
About Button Groups
Buttons in a group are surrounded by a parent with the
.slds-button-group class, unless they are in a list (in which case they use
.slds-button-group-list. If the last button is an icon, like the down triangle, use the
.slds-button_icon-border-filled class when accompanying a
If the last button in a group needs to be wrapped in another element (for example, a drop-down trigger), add the
.slds-button_last class to the wrapper element to create proper spacing and borders.
Unless you are using the list version, include the Aria role
role="group" so that assistive technologies are alerted to the grouping.