Before this commit, buttons to remove checkboxes and buttons to re-order checkboxes were styled like button. After this commit, buttons are just icons. We also improve a little bit the design of the checkbox list (add space between elements and a light border between items in the checkbox list). task-2312878 closes odoo/odoo#58181 X-original-commit: 0253b01632a30adfe071aa090a875fb3915e1962 Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>