feel free to keep it strictly simple...
load css

Old(er) WebsiteBaker-Modules often do something like this:

   // check if frontend.css file needs to be included into the <body></body> of view.php
   if((!function_exists('register_frontend_modfiles') || !defined('MOD_FRONTEND_CSS_REGISTERED')) && file_exists(WB_PATH .'/modules/modpath/frontend.css')) {
 	echo '<style type="text/css">';
       include(WB_PATH .'/modules/modpath/frontend.css');
       echo "\n</style>\n";

This is some kind of waste from older WB versions, before the register_frontend_modfiles() method was introduced.

As register_frontend_modfiles() is already marked as deprecated, this code will lead to invalid (X)HTML sooner or later.

It is neither necessary nor useful to add this code to your module!

Lepton will handle this for you! See templates/page_headers for more details.