CSS Minifier

The minifier makes four passes over your stylesheet:

1. Deletes every /* … */ comment.
2. Collapses all whitespace, line breaks included, to single spaces.
3. Removes the spaces around { } : ; , > + ~.
4. Drops the last semicolon before each closing brace.

The sample on the page goes from 117 characters to 73:

That's all it does. It doesn't shorten 0.9 to .9, rewrite colours, merge duplicate selectors or drop unused rules, so the output is easy to compare with your source when something looks off.

Removing spaces around + and : is usually harmless, but not always:

• Addition inside calc(): CSS needs spaces around + there. calc(1em + 4px) becomes calc(1em+4px), which browsers reject, so the whole declaration is ignored. Subtraction is safe, because the tool leaves spaces around - alone: calc(100% - 2 * 10px) comes through intact. Rewrite additions as calc(1em - -4px), or fix them in the output by hand.
• A space before a pseudo-class: article :first-child means any first child inside an article. Minified, it becomes article:first-child, an article that is itself a first child. If you rely on that space, write article *:first-child instead, which minifies safely.

Media queries are fine: @media (min-width: 600px) and (max-width: 900px) comes out as @media (min-width:600px) and (max-width:900px), with the spaces around and kept.

The tool doesn't recognise quoted strings, so the whitespace and comma rules apply inside them. content: "a , b" becomes content:"a,b", which changes what the page displays. Check any content values and quoted font names with unusual spacing.

Licence comments go too. Many libraries start theirs with an exclamation mark right after the opening /* so tools keep them, but this minifier removes every comment, including those. If a licence requires the notice to stay with the code, paste it back at the top of the minified file.