This commit adapt several components and utility-classes in order to increase visual contrast. In the case of `o-mail-ActivityGroup` and `o-mail-NotificationItem` templates, these has been reworked in order to use default BS components and consequently automatically inheriting the improved design. task-3338419 closes odoo/odoo#124903 Part-of: task-3326263 X-original-commit: 190ec1c947e17b2b4aa8614e9e0a04d00cb38d90 Related: odoo/enterprise#42507 Signed-off-by: Bruno Boi (boi) <boi@odoo.com> Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>