MVC Bundling breaking my calc CSS statements by removing spaces?

In addition to the answer above: if you use:

margin-left: calc((50%) + 480px);

You should rewrite it as:

margin-left: calc((50%) - -480px);

Since it didn't seem to fix (50%)+ for me.

This is an issue of the optimizer.

To avoid the miniffier to remove the whitespaces, group the affected element with parenthesis. That workarrounds the issue.

margin-left: calc((50%) - 480px);

If the default css minification is not doing what you need, you can always use a third party one.

bundling allows you to use your own transformations using IBundleTransform

var bundle = new Bundle("~/Content/css", myCustomCssTransform);

there are many different bundlers - nuget

for example you could use YUI compressor:

    using System.IO;
using System.Web.Optimization;
using Yahoo.Yui.Compressor;

namespace Bundler.Utilities
{
 public enum contentType
 {
  javascript,
  css
 }

 public class YUITransform : IBundleTransform
 {

  readonly string _contentType = string.Empty;

  public YUITransform(contentType contentType)
  {
   if (contentType == contentType.css)
   {
    this._contentType = "text/css";
   }
   else
   {
    this._contentType = "text/javascript";
   }
  }

  public void Process(BundleContext context, BundleResponse bundle)
  {
   bundle.ContentType = this._contentType;

   string content = string.Empty;


   foreach (FileInfo file in bundle.Files)
   {

    using (StreamReader fileReader = new
StreamReader(file.FullName)) {
     content += fileReader.ReadToEnd();
     fileReader.Close();
    }

   }

   bundle.Content = Compress(content);
  }

  string Compress(string content) {

   if (_contentType == "text/javascript")
   {
     return JavaScriptCompressor.Compress(content);
   }
   else
   {
    return CssCompressor.Compress(content,
                           CssCompressionType.StockYuiCompressor
);
   }
  }
 }
}