python-lightningcss

python-lightningcss offers PyO3 bindings to the lightningcss library. Presently only a subset of functionality is exposed, intended for integration into a Python-centric web application rather than a JavaScript-based workflow. If the latter is needed, consider using the official npm lightningcss module, parcel, or webpack instead.

Installation

python-lightningcss includes wheels which can be installed for most platforms using pip:

$ pip install lightningcss

Alternatively, python-lightningcss may be installed directly from source:

$ pip install git+https://github.com/pydsigner/python-lightningcss

This will require that the Rust toolchain be installed.

Usage

import lightningcss

parser_flags = lightningcss.calc_parser_flags(nesting=True)

input_css = """
.navbar {
    margin: 0;

    a {
        padding-left: 0;
        padding-right: 0;
        padding-top: 5px;
        padding-bottom: 5px;
    }
}
"""

output_css = lightningcss.process_stylesheet(
    input_css,
    filename="abc.css",
    parser_flags = parser_flags,
    browsers_list = ['defaults'],
    minify = True,
)

The filename keyword parameter is only used for displaying error messages from the parser. When using browsers_list, lightningcss will try to transpile the code to be compatible with the specified browserslist target.

This package also supports creating a CSS bundle where all @import rules are resolved into a single stylesheet:

bundled_css = lightningcss.bundle_css(
    "main.css",
    browsers_list = ["defaults"],
    minify = False,
)

All resources referenced via @import are resolved relative to the main file.