Since [1] the CSS property reset for hovered outline buttons is using invalid property values. After this commit the color and image are only reset on non-hover: - the `background-color` is already set to `none` by `.btn`, - the `background-image` is only set if defined on the button's style - there is no need to reset it. [1]: https://github.com/odoo/odoo/commit/a010c91b5ee119cf54ed1a68a6ea06b2bc5f3978 task-2633169 closes odoo/odoo#86699 X-original-commit: 8530235bff30bfcad55cf39927f0733d30fe2eee Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>