You can stylize the dashboard admin area with the custom CSS. Here is the snippet code you need to paste into functions.php file. Replace the comment with your custom code.
“admin_head is an action event and can be hooked by add_action hook. The action refers on the admin area and everything you include here will be applied only on the admin side. ”
add_action('admin_head', 'my_custom_acode');
function my_custom_acode() {
echo '<style>
/* your code here */
</style>';
}
Please let us know in the comments if everything worked as expected. We have tested this code with the Version: 4.0.1 of the Divi Theme and Divi Friendly Hosting with PHP 7.3 and WordPress 5.2.4.
If you think this code saved you time, we will be happy to receive a comment! 
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License: This snippet is from https://codex.wordpress.org, copyright WordPress, Licensed under the GNU General Public License, no warranty; click here for details.
perfect
It works perfectly. Thank you
Hi,
It works perfectly. I opted to separate it and put it in an external file and use wp_enqueue_style() for better future maintenances.
J