wp-admin/css/colors/_mixins.scss
/*
 * Button mixin- creates 3d-ish button effect with correct
 * highlights/shadows, based on a base color.
 */
@mixin button( $button-color, $text-color: white ) {
	background: $button-color;
	border-color: darken( $button-color, 10% );
	color: $text-color;
	box-shadow: inset 0 1px 0 lighten( $button-color, 15% ), 0 1px 0 rgba(0,0,0,.15);

	&:hover,
	&:focus {
		background: darken( $button-color, 5% );
		border-color: darken( $button-color, 15% );
		color: $text-color;
		box-shadow: inset 0 1px 0 lighten( $button-color, 10% );
	}

	&:focus {
		box-shadow: inset 0 1px 0 lighten( $button-color, 10% ),
		            0 0 0 1px #5b9dd9,
		            0 0 2px 1px rgba( 30, 140, 190, .8 );
	}

	&:active {
		background: darken( $button-color, 10% );
		border-color: darken( $button-color, 15% );
		color: $text-color;
	 	box-shadow: inset 0 2px 5px -3px rgba( 0, 0, 0, 0.5 ),
		            0 0 0 1px #5b9dd9,
		            0 0 2px 1px rgba( 30, 140, 190, .8 );
	}

	&[disabled],
	&:disabled,
	&.button-primary-disabled,
	&.disabled {
		color: hsl( hue( $button-color ), 10%, 80% ) !important;
		background: darken( $button-color, 8% ) !important;
		border-color: darken( $button-color, 15% ) !important;
		text-shadow: none !important;
	}
}
