In this guide, we'll be changing the default classic admin theme to the very popular Reno theme.
Install the Reno module.
 
                      /**
 * Default admin theme
 *
 * Module name of default admin theme for guest and users that haven't already selected one
 *
 * Core options include: **AdminThemeDefault** or **AdminThemeReno**.
 * Additional options will depend on what other 3rd party AdminTheme modules you have installed.
 *
 * @var string
 *
 */
$config->defaultAdminTheme = 'AdminThemeReno';Refresh your page, and bingo! Enjoy your new admin theme!
