LESS minifier breaking media queries on possible comment parse

[bmcminn]

Posted this initially on the PrePros issues, https://github.com/sbspk/Prepros/issues/55

Problem persisted when minifying compiled LESS file with native LESS minifier with PrePros 1.5 on Windows 7 64-bit. Confirmed this same problem in Codekit's use of the LESS minifer (YUI compression) on Mac OSx 10.8.

EDIT: Possibly related issue #284

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Noticed this in Chrome Version 27.0.1453.94m however it doesn't seem to affect FF 21, not sure about others.

This is a default media query definition per main.css - line 223 in the HTML5 Boilerplate template.

@media print,
       (-o-min-device-pixel-ratio: 5/4),
       (-webkit-min-device-pixel-ratio: 1.25),
       (min-resolution: 120dpi) {
    /* Style adjustments for high resolution devices */
    // a {
    //   font-size: 4rem;
    // }
}


/**===================================================**\
/**  PRINT STYLES
/**===================================================**/
@media only print {
  // *                             { background: @trans !important; box-shadow: none !important; color: @black !important; text-shadow: none !important; }
  a,
  a:visited                     { text-decoration: underline; }
  a[href]:after                 { content: " (" attr(href) ")"; }
  abbr[title]:after             { content: " (" attr(title) ")"; }

  /** MANUALLY TRUNCATED FOR BREVITY **/
}

When compressing the above LESS/CSS, the minified source breaks resulting in the following result:

@media print,(-o-min-device-pixel-ratio:5/@media only print{a,a:visited{text-decoration:

Looks like the minifier has an issue with / chars in @media definitions and I'm assuming treats it as a delimiter for a comment.

This particular issue causes @media scope to bleed into my only print media query, so my print styles are shown regardless of which media mode is enabled when my compressed CSS file is being used.

[lukeapage]

Looks to be a bug in ycssmin - if you just use the basic compressor then you don't get any problem

[lukeapage]

both ycssmin and cssmin which we used before that don't seem to be getting alot of development. https://npmjs.org/package/clean-css looks like it does.. we should consider switching. @jonschlinkert @matthew-dean do you know of any other node css minifiers and have any preferences?

[lukeapage]

related: #1080

[lukeapage]

clean css also has a issue - clean-css/clean-css#117
I think its caused by the *\ at the bgeining of the print styles comment block

[GoalSmashers]

It's fixed in clean-css 1.0.11. It was related to escaping new line breaks. Enjoy :)