CSS Minifying not compatible with CSS3 calc() function

[sydekumf]

Preconditions

1. I use Magento 2.1.4 and the following extension: https://github.com/Magenerds/PageDesigner
2. CSS Minifying and Merging is enabled in system configuration

Steps to reproduce

1. Install the extension mentioned above OR inject your own CSS using calc(). You can see here the calc() css of the mentioned extension
2. Open the site where this css gets rendered (for the extension it is a cms page in the backend)

Expected result

1. The minified css should be calc((100% / 12 * 1) - 10px);

Actual result

1. The minified css is instead calc((100%/12*1)- 10px); (no whitespaces) and therefore it will not be rendered correctly.

[sippsolutions]

Can be reproduced. The magento minifying process seems to remove whitespace inside the calc()-statement.

[KrystynaKabannyk]

hello @sydekumf, thank you for the report, the internal ticket is created MAGETWO-66482.

[magento-team]

Internal ticket to track issue progress: MAGETWO-67487