Minifier is breaking some CSS, specifically calc(100% + 5px)

[khmelevskii]

.issue {
    width: calc(100% + 30px);
}

turns into
.issue{width:calc(100%+30px)}
instead of
.issue{width:calc(100% + 30px)}

Notice the missing spaces

[yogthos]

CSS minification is handled by the YUI Compressor library, so it looks like it might be a bug there. Asset minifier is on the latest version, so one approach might be to look for an alternative library.

[kengruven]

Looks like yui/yuicompressor#268 to me. Strangely, that issue was recently closed, without comment, and with any recent changes.

[yogthos]

It looks like it might be worth looking at other options if the yuicompressor isn't actively maintained.