Modular Custom CSS reloaded

gistfile1.phtml

/**
 * Enable Administrators to add a Custom CSS Control to the Customiser.
 */
function onehundred_enable_custom_css() {

        if ( current_user_can('create_users') ) {

	      function onehundred_enable_custom_css_option() {
		    register_setting('general', 'onehundred_enable_custom_css', 'wp_filter_nohtml_kses');
		    add_settings_field('onehundred_enable_custom_css', __('Enable Custom CSS?', 'onehundred') , 'onehundred_enable_custom_css_form', 'general');
	      }
	      add_filter('admin_init', 'onehundred_enable_custom_css_option');
	      
	      function onehundred_enable_custom_css_form() {
                        $access = get_option('onehundred_enable_custom_css', 'no');
                        $current_theme = wp_get_theme();
                        $current_theme = $current_theme->stylesheet;
                        ?>
		    <select id="onehundred_enable_custom_css" name="onehundred_enable_custom_css" value="<?php echo $access; ?>">
			  <option value="no" <?php selected('no' == $access); ?>><?php _e('No', 'onehundred'); ?></option>
			  <option value="yes" <?php selected('yes' == $access); ?>><?php _e('Yes', 'onehundred'); ?></option>
		    </select>
                        <p class="description"><?php _e('<strong>Advanced Users Only.</strong> If Custom CSS support is enabled, a new control will be added to the', 'onehundred'); ?>
                        <a href="<?php echo admin_url(); ?>customize.php?theme=<?php echo $current_theme; ?>"><?php _e('Customizer.', 'onehundred'); ?></a></p><?php 
	      }

                $access = get_option('onehundred_enable_custom_css', 'no');
                if ( $access == 'yes' ) { 
                        function onehundred_custom_css_customize_register($wp_customize) {
                                $wp_customize->add_section('custom_theme_css', array(
                                        'title'                 => __('Custom CSS', 'onehundred'),
                                        'priority'              => 105,
                                ) );
                                $wp_customize->add_setting('custom_theme_css' , array(
                                        'transport'             => 'postMessage',
                                        'sanitize_callback'     => 'onehundred_sanitize_text_input',
                                ) );
                                $wp_customize->add_control('custom_theme_css', array(
                                        'section'               => 'custom_theme_css',
                                        'type'                  => 'textarea',
                                ) );
                        }
                        add_action('customize_register','onehundred_custom_css_customize_register');
                }

        }

        function onehundred_custom_css_wp_head() {
                $custom_theme_css = get_theme_mod('custom_theme_css', '');
                echo '<style type="text/css" id="custom-theme-css">' . $custom_theme_css . '</style>';
        }
        add_action('wp_head', 'onehundred_custom_css_wp_head');

}
add_action('init', 'onehundred_enable_custom_css');