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

// NOTE: These remain for the styling of buttons that are NOT blocks and is used elsewhere.  This can be removed when those no longer exist.
// See https://github.com/WordPress/gutenberg/issues/29167
@mixin button-main-styles {
	@include button-padding-styles;
	@include button-typography-styles;
	@include button-color-styles;
	border-radius: var(--wp--custom--button--border--radius);
}

@mixin button-color-styles {
	opacity: 1;
	color: var(--wp--custom--button--color--text);
	background-color: var(--wp--custom--button--color--background);
	border-color: currentColor;
	svg {
		fill: var(--wp--custom--button--color--text);
	}
}

//standard Button padding.  Account for desired padding size and the size of the border width (so that the total height of
//standard and outline buttons are equal.
@mixin button-padding-styles {
	border-width: 0;
	padding-top: calc( var(--wp--custom--button--spacing--padding--top) + var(--wp--custom--button--border--width) );
	padding-bottom: calc( var(--wp--custom--button--spacing--padding--bottom) + var(--wp--custom--button--border--width) );
	padding-left: calc( var(--wp--custom--button--spacing--padding--left) + var(--wp--custom--button--border--width) );
	padding-right: calc( var(--wp--custom--button--spacing--padding--right) + var(--wp--custom--button--border--width) );
}

@mixin button-typography-styles {
	font-weight: var(--wp--custom--button--typography--font-weight);
	font-family: inherit;
	font-size: var(--wp--custom--button--typography--font-size);
	line-height: var(--wp--custom--button--typography--line-height);
	text-decoration: none; // Needed because link styles inside .entry-content add a text decoration
}

//apply outline styles. apply padding that does NOT account for border width (as the border width is applied here).
@mixin button-border-styles {
	border-style: var(--wp--custom--button--border--style);
	border-width: var(--wp--custom--button--border--width);
	padding-top: var(--wp--custom--button--spacing--padding--top);
	padding-bottom: var(--wp--custom--button--spacing--padding--bottom);
	padding-left: var(--wp--custom--button--spacing--padding--left);
	padding-right: var(--wp--custom--button--spacing--padding--right);
}


// NOTE: These remain for the hover styling of blocks.  This can be removed when the button block has configurable hover states.
// The mechanism below ONLY CHANGES CSS VARIABLES that are already applied to properties (above)
// See https://github.com/WordPress/gutenberg/issues/4543
@mixin button-hover-styles {
	//The following changes should ONLY be changed if the user has NOT set a custom color
	&:not(.has-background):not(.has-text-color) {
		&:hover,
		&:focus,
		&.has-focus {
			//change the color variables to the hover equivalent
			--wp--custom--button--color--text: var(--wp--custom--button--hover--color--text);
			--wp--custom--button--color--background: var(--wp--custom--button--hover--color--background);
			--wp--custom--button--border--color: var(--wp--custom--button--hover--border--color);
			@include button-color-styles;
			border-color: var(--wp--custom--button--border--color);
		}
	}
}

//Mixins for the alternative outline style
@mixin button-outline-hover-styles {
	&:hover,
	&:focus,
	&.has-focus {
		border-style: var(--wp--custom--button--border--style);
		border-color: currentColor;
		border-width: var(--wp--custom--button--border--width);
		padding-top: var(--wp--custom--button--spacing--padding--top);
		padding-bottom: var(--wp--custom--button--spacing--padding--bottom);
		padding-left: var(--wp--custom--button--spacing--padding--left);
		padding-right: var(--wp--custom--button--spacing--padding--right);
	}
}