themes-wordpress/blockbase/sass/blocks/_button.scss

@import 'button-mixins';
/**
 * Button
 */

/**
 * Block Options
 */
 .wp-block-button, .wp-block-button__link {
	&.wp-block-button__link,
	.wp-block-button__link {
		@include button-hover-styles;
		@include button-padding-styles;
		text-decoration: none;
		font-weight: var(--wp--custom--button--typography--font-weight);
	}
	&.is-style-outline {
		&.wp-block-button__link,
		.wp-block-button__link {
			--wp--custom--button--color--text: var(--wp--custom--button--border--color);
			--wp--custom--button--color--background: transparent;
			@include button-border-styles;
			@include button-hover-styles;
			@include button-color-styles;
		}
	}
}

// TODO: I'm not sure what the end goal should be here, but since we are unable to use
// a button block OUTSIDE of the context of the button collection block (grrrrrrrrr)
// then there are undesired margins to be dealt with somehow.
.wp-block-buttons {
	.wp-block-button:last-child {
		margin-bottom: 0;
	}
}