Kirki

custom.php

<?php
Kirki::add_field( 'gs', array(
	'type'        => 'color',
	'settings'    => 'my_setting',
	'label'       => __( 'Header Background Color', 'my_textdomain' ),
	'section'     => 'my_section',
	'default'     => '#0088CC',
	'priority'    => 10,
	'output'     => array(
		array(
			'element'  => '.site-header',
			'property' => 'background-color',
      'suffix' => '!important'
		),
	),
) );