The following attributes are available:

btn-background: A button background value.
btn-background-active: A button background value, when active.
btn-background-hover: A button background value, when hover.
btn-border-active: A button border value, when active.
btn-border-color: A button border color value.
btn-border-focus: A button border value, when focus.
btn-border-hover: A button border value, when hover.
btn-border-radius: A button border radius value.
btn-box-shadow-focus: A button box shadow, when focus.
btn-color: A button color value.
btn-color-active: A button color value, when active.
btn-color-hover: A button color value, when hover.
btn-cursor: A button cursor value.
btn-font-family: A button font-family value.
btn-href: A URL for the button.
btn-line-height: A button line-height value.
btn-size: A button size value.
btn-text-decoration: A button text decoration value.
btn-text-decoration-active: A button text decoration value, when active.
btn-text-decoration-focus: A button text decoration value, when focus.
btn-text-decoration-hover: A button text decoration value, when hover.
btn-type: A button type value.
btn-vertical-align: A button vertical alignment value.
menu-animation-speed: A unit of time in seconds for how fast the expand or collapsed animation operates.
menu-border: A menu border value.
menu-border-display: A menu border display value.
menu-border-radius: A menu border radius value.
menu-flex-direction: A menu flex direction value.
menu-item-margin: A menu item margin value.
menu-padding: A menu padding value.
menu-theme-variant: The name of a theme variant to use on the dropdown.
menu-width: A menu width value.
menu-x-offset: A menu x-offset value.
menu-y-offset: A menu y-offset value.
placement: A value representing where to place the menu on expand.
toggle-on: One of click or mouseover.
openDelay: A unit of time in milliseconds for how long to wait before auto-expanding.
theme-variant: The name of a theme variant to use for the dropdown.