Correction of the position of the buttons when editing bg-image position with a parallax effect other than "fixed". task-46147 closes odoo/odoo#48419 X-original-commit: 0919b11c9a78a97345b42bf0fe0f1f9939c2b214 Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>