get_theme_mod

gistfile1.txt

/**
 * 鐵人賽示範：自訂背景顏色
 *
 * @return void
 */
function ironman_customizer_css() {
	$background_color = get_theme_mod( 'ironman_background_color_setting', '#ffffff' );
	?>
	<style type="text/css">
		body {
			background-color: <?php echo esc_attr( $background_color ); ?>;
		}
	</style>
	<?php
}

add_action( 'wp_head', 'ironman_customizer_css' );