
By including beans_remove_action( 'beans_content_template' );
you've removed the content area (that is, content written using the normal WP editor). There's nothing wrong with the CSS, but without any content the .tm-main
element has no height which is why you're not seeing the background.
If you really want the content area gone, you could try doing this in page templates...
add_action( 'beans_main_append_markup', 'some_content' );
function some_content() {
?>
<p>this is some content</p>
<?php echo get_some_custom_field(); ?>
<?php
}

First of all, thank you so much for answering so quickly!
actually, my goal is to create a "site conteiner" similar to this: []https://demos.restored316designs.com/bloom/layouts/sc/)
any idea?

Maybe a center UIkit grid will do the magic...
https://getuikit.com/v2/docs/grid.html
What do you think?

Hello,
What do you want to do exactly ?
Center the logo of your header ? A quick search in the Beans Forum : https://community.getbeans.io/discussion/logo-between-menu/#post-3556. Maybe it helps ?
Do you want to display the sidebar to the left ? Then, in the WP customizer, choose the appropriate layout.
If you want efficient help, I would advise you to be more specific in the questions you ask and in the title of the tickets you open. I'm afraid that "Beans newbie trying to develop a theme from scratch" does not encourage people to help you... 🙁
Mathieu