minify css and calc function bug report

I revive some other’s posts about an unresolved issue:
https://wordpress.org/support/topic/minify-css-and-calc-function/
https://wordpress.org/support/topic/css-minify-removes-mandatory-spaces-in-calc/

they say the third is the good one.

I cannot be more precise than cmeeren, my example is just marginally different.
Take any wp theme;
in w3tc turn on “minify” with “CSS minifier: Minify”
and “Inline CSS minification”;
in the customizer css add any rule that use calc(), like
body{font-size:calc(100px + 10px);}
and in the output you get
body{font-size:calc(100px+10px)}
which is invalid and discarded.

BUT if I choose “CSS Tidy” as minifier the rule is preserved and everything works (and the performance is almost the same if not better).

I don’t know if you are using a third party library for minification or not, but a very very simple thing you can do is change the default minifier from Minify to Css Tidy. The malfunctions would drop to 0!

Bye, let me know.