This PR improves the style of the kanabn actiivty popover after the wowl refactoring. It focuses on: - Restoring button hover style - Restoring scroll behavior for multiple activities - Restoring text ellipsis on long activity summary/name - Centering mark done buttons task-2998139 closes odoo/odoo#102983 X-original-commit: 2cebfd9 Related: odoo/enterprise#32667 Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>