Minify CSS

CSS

Strips whitespace and comments, then rewrites CSS to the smallest equivalent form.

Filter rewrite_css · Filter docs

A mod_pagespeed 1.15 filter. ModPageSpeed 2.0 applies it as part of one always-on pipeline, not as a separate switch.

Both frames render identically — that's the goal. The win is in the bytes and requests below, not the look. They're served live by mod_pagespeed 1.15 on demo-httpd-1.1.modpagespeed.com; the optimized frame applies only this filter. Right after a cache purge it may briefly match the original while the worker rewrites it — reload to see the result.

Measured impact

Total bytes

721 B 588 B

−18%

HTML size

685 B 558 B

−19%

What changed in the source

The page's HTML, before and after this filter. Red lines are removed, green lines are added.


                
                  
                        <html>
                    

                          <head>
                    

                            <title>rewrite_css example</title>
                    

                      -     <style type='text/css'>
                    

                      -       #iddy, #anotherId {
                    

                      -         /* This comment will be stripped.*/
                    

                      -         border: solid 1px #cccccc;
                    

                      -         padding: 1.2em;
                    

                      -         float: left;
                    

                      -         color:WindowText;
                    

                      -       }
                    

                      -       div.classy span, div.classy img {
                    

                      -         display: block;
                    

                      -         border: none !important;
                    

                      -         background: none !important;
                    

                      -       }
                    

                      -     </style>
                    

                      -     <link rel="stylesheet" type="text/css" href="styles/yellow.css">
                    

                      +     <style type='text/css'>#iddy,#anotherId{border:solid 1px #ccc;padding:1.2em;float:left;color:WindowText}div.classy span,div.classy img{display:block;border:none!important;background:none!important}</style>
                    

                      +     <link rel="stylesheet" type="text/css" href="styles/A.yellow.css.pagespeed.cf.KM5K8SbHQL.css">
                    

                          </head>
                    

                          <body>
                    

                            <div class="blue yellow big bold">

Run this on your own site

This is one of 47 filters mod_pagespeed 1.15 applies in place — self-hosted on Apache, nginx, and IIS. Install and run it: it optimizes right away and adds an X-PageSpeed-Warn: unlicensed header until you license it. A commercial license is required for production use.

Download & run

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