Spaces are mandatory inside CSS calc() function, and should not be removed in inlining.
.foo {
width: calc(100% - 80px);
}
gets parsed to this
.foo {width: calc(100%-80px);}
and that doesn't work in the browser.
linear-gradient also has the same issue.
linear-gradient(135deg, #00689b 0%, #00375a 90%, #00375a 90%, #003455 100%);
gets parsed to this
linear-gradient(135deg, #00689b0%, #00375a90%, #00375a90%, #003455100%);