Minification Options

Remove comments

Strip all /* … */ blocks

Remove whitespace

Collapse spaces, tabs, newlines

Remove last semicolons

Drop trailing ; before }

Compress colors

#ffffff → #fff, rgb(0,0,0) → #000

Remove empty rules

Delete .foo { } blocks

Compress zero units

0px 0em 0rem → 0

Input CSS

Parse warning

CSS minification strips everything the browser doesn't need to parse the stylesheet:

→ Comments are decorative - the browser ignores them anyway

→ Whitespace (spaces, tabs, newlines) is only for readability

→ Trailing semicolons before } are optional in CSS

→ Color shorthands: #ffffff → #fff

Before (76 bytes)

/* Main heading */
h1 {
  color: #ffffff;
  margin: 0px;
}

↓ minified

After (21 bytes)

h1{color:#fff;margin:0}

72% smaller

Always keep your original unminified source in version control - minified code is not easily editable.

Serve minified CSS with Content-Encoding: gzip for further compression (typically another 70-80%).

Use a build tool (Vite, Webpack, PostCSS) to automate minification so you never forget to minify before deploying.

CSS Minifier