Description of the issue/feature this PR addresses: --- When a user chooses "Repeat Pattern" as the background image position, nothing happens. Current behavior before PR: --- As the background size is set to auto, for background-position `repeat-pattern` no effect[1] can be seen in the background size. [1]: https://bit.ly/3MM31Ac Desired behavior after PR is merged: --- Not a bug but can be considered an improvement in features by setting some default[2] width or height for a repeat-pattern option for all relevant snippets. [2]: https://bit.ly/3GbGIBo task- 2862510 closes odoo/odoo#102995 Signed-off-by: Romain Derie (rde) <rde@odoo.com>