Hello,

I tried to use your example here from documentation: div.wpb_content_element .ui-tabs .ui-tabs-nav li, div.wpb_content_element .ui-accordion .ui-accordion-header, div.wpb_tabs .ui-tabs .ui-tabs-panel { background-color: #ff0000; }

If I put it in the style.css from powermag-theme-folder it's not working. If I create a new style.css and put it in the powermag/css folder itÄs also not working. Other themes are working fine with this. If I put it over customizer in the additional css field (it's working with other code like setting background for body but not with the code from documentation) it's also not working. If I create a child theme and import my style I have big font and also nothing happent. Why?

Btw if I create a child theme I have big font etc.:

functions.php (from child)

<?php
/**
 * Powermag Child functions and definitions
 *
 * @package Powermag
 *
 */
/**
 *  Enqueue scripts and styles.
 */
function theme_coder_child_scripts() {
// Enqueue Parent Stylesheet
wp_enqueue_style( 'powermag-parent-stylesheet', get_template_directory_uri() . '/style.css' );
} // powermag_child_scripts
add_action( 'wp_enqueue_scripts', 'powermag_child_scripts' );
/* You can add your own php functions and code snippets below */

And if I am using for example 

.site-header
{

background-image: url("mysite url") ! important;

}

it's not working.

" If it doesn't work It's likely that Visual Composer classes names have changed over the years so that code isn't valid anymore."

--> You said it is not necessary to use visual composer and I didn't install it. 

Here is my solution for the future:

style.css:

/* 
Theme Name: powermag child theme
Theme URI: http://www.
Description: Theme 
Author: WebsiteBundles
Author URI: http://
Template: powermag
Version: 1.0.0
Text Domain: powermag-child
-------------------------------------------------------------- */ 

/* =Theme customization starts here
------------------------------------------------------- */

#################################################################

functions.php

<?php 
add_action( 'wp_enqueue_scripts', 'theme_enqueue_styles' );
function theme_enqueue_styles() 
{
wp_enqueue_style( 'parent-style', get_template_directory_uri() . '/style.css' );
wp_enqueue_style( 'child-style', get_stylesheet_directory_uri() . '/style.css', array('parent-style') );
}
?>

Important: very important because otherwise you can get a white screen if you updatet a post or something like that. Therefore it's recommended to remove all white spaces and lines in the functions.php !!!!!!!!!!!!!!!!