cssmin - YUI CSS Compressor

0.2.0 · maintenance · verified Fri Apr 17

A Python port of the YUI CSS compression algorithm, providing minification for CSS files. The library is currently at version 0.2.0 and has seen minimal updates recently, suggesting a stable but slow release cadence. It aims to replicate the functionality of the original YUI Compressor for CSS.

Common errors

```
ModuleNotFoundError: No module named 'cssmin'
```
cause The `cssmin` package is not installed in your current Python environment.

fix Install the package using pip: `pip install cssmin`
```
AttributeError: module 'cssmin' has no attribute 'compress'
```
cause You are attempting to call a non-existent compression function. The primary function for minification in the `cssmin` library is `cssmin.cssmin()`.

fix Use the correct function name: `minified_css = cssmin.cssmin(css_string)`
```
TypeError: expected string or bytes-like object, os.PathLike object given
```
cause You are trying to pass a file path (or a `Path` object) directly to `cssmin.cssmin()` instead of the actual CSS content from the file.

fix Read the content of your CSS file into a string first, then pass the string to the minifier: ```python with open('your_style.css', 'r') as f: css_content = f.read() minified_css = cssmin.cssmin(css_content) ```

Warnings

gotcha The `cssmin` library is based on the YUI CSS compression algorithm, which was last updated in 2011. This means it may not fully support modern CSS features (e.g., custom properties/variables, `calc()`, newer pseudo-classes, grid/flexbox syntax) introduced after this period. Using it with complex, modern CSS might lead to incorrect minification, malformed output, or outright errors.
Fix: For projects requiring support for modern CSS features and standards, consider more actively maintained CSS minifiers like `rcssmin`, `cssutils`, or external JavaScript-based tools such as PostCSS with `cssnano` or `clean-css`.
gotcha The `cssmin` library has not been actively maintained since 2021. While it remains stable for its intended purpose, this lack of active development means bug fixes for new edge cases, performance improvements, or support for future Python or CSS standard changes are unlikely.
Fix: Evaluate alternatives such as `rcssmin` (which aims for higher performance and correctness for modern CSS), `cssutils`, or external frontend build tools if your project requires ongoing maintenance, active support, or cutting-edge features.
gotcha The `cssmin.cssmin()` function expects a string containing the CSS content to be minified, not a file path. Passing a `Path` object or a string representing a file path directly will result in a `TypeError`.
Fix: Ensure you read the CSS file content into a string before passing it to the minifier. For example: `with open('style.css', 'r') as f: css_content = f.read(); minified = cssmin.cssmin(css_content)`.

Install

pip install cssmin Install latest version

Imports

cssmin
```
import cssmin
```
The primary minification function is accessed via `cssmin.cssmin()` after importing the module.

Quickstart

This quickstart demonstrates how to import the `cssmin` library and use its `cssmin()` function to minify a string of CSS content. The output will show the minified CSS and its reduced size.

import cssmin

css_content = """
body {
    font-family: Arial, sans-serif;
    color: #333;
}
h1 {
    margin-bottom: 10px;
    /* This is a comment */
    padding: 5px;
}
"""

minified_css = cssmin.cssmin(css_content)

print("Original CSS size:", len(css_content), "bytes")
print("Minified CSS size:", len(minified_css), "bytes")
print("Minified CSS:\n", minified_css)

view raw JSON →