TinyMCE Wordpress: How to set the style to be displayed when editing?

Question

TinyMCE

I prescribe my class in additional styles in the theme settings. I apply it to the tag When viewing the page, everything is displayed correctly, but nothing is visible in the editor. How can I make this style work in the editor as well? I don’t know if it’s relevant or not, but in the editor settings there is an empty checkbox<div class="moyclass">содержание</div>

Creating a CSS class menu
Load the CSS classes used in editor-style.css and replace the Formats menu.

In it is written

ERROR : Your theme does not support editor-style.css. To use this option, add editor-style.css to your theme or child theme. Enabling this option will also load the stylesheet into the editor.

Answer 1

Add to your theme's functions.php file:

function my_theme_add_editor_styles() {
  add_editor_style( 'editor-styles.css' );
}
add_action( 'current_screen', 'my_theme_add_editor_styles' );

And make a custom stylesheet for the editor:editor-styles.css