If you want to create a new page for developers, you should create it on the Moodle Developer Resource site.


From MoodleDocs

Styling standard page elements and parts

Moodle developers come from many different backgrounds with different levels of experience. In the past we have tried to define standards for styling components, but this has been implemented inconsistently.

As of Moodle 3.2 the recommendation is for all developers to learn how to apply the classes and components from Bootstrap in order to create the page layouts and components they want to achieve. Custom HTML and styles are strongly discouraged.

See also

W3C validation