CleanCSS CleanCSS is a simple pythonic language for CSS inspired by CleverCSS but simpler and with less obstrusive features.

Why I really liked the idea behind CleverCSS but when used in production I realized that I was trying to get away from its parser by escaping strings and unsupported CSS properties way too often. Using vendor prefixes like -webkit-gradient and values such as rgba resulted in a messy CSS, so I decided to write my own parser for a similar syntax without all the complex features that I did not use anyway and it now works fine for me in REAL modern websites.

Syntax examples I'm going to keep the CleverCSS examples where possible since the syntax is really similar. A small example below. Note the indentation based syntax and how you can nest rules: #header, #footer: margin: 0 padding: 0 font-> family: Verdana, sans-serif size: .9em li: padding: 0.4em margin: 0.8em 0 0.8em h3: font-size: 1.2em p: padding: 0.3em p.meta: text-align: right color: #ddd Of course you can do the very same in CSS, but because of its flat nature the code would look more verbose. The following piece of code is the CleanCSS output of the above file: #header, #footer { margin: 0; padding: 0; font-family: Verdana, sans-serif font-size: .9em } #header li, #footer li { padding: 0.4em; margin: 0.8em 0 0.8em; } #header li h3, #footer li h3 { font-size: 1.2em; } #header li p, #footer li p { padding: 0.3em; } #header li p.meta, #footer li p.meta { text-align: right; color: #dddddd; }

Callbacks Starting with version 1.4 CleanCSS supports user callbacks to alter the resulting stylesheet. The callback function receives the property name and its value and should return a list of property-value pairs to insert in the generated CSS. Example: import cleancss def callback(prop, value): rules = [] # Include the unaltered rule rules.append( (prop, value) ) # Include a variant of the rule rules.append( ("-moz-"+prop, value) ) return rules with open('file.ccss') as f: print cleancss.convert(f, callback) The library already includes a callback function that can be used to convert between the most common browser variants Example: import cleancss with open('file.ccss') as f: print cleancss.convert(f, cleancss.callbacks.browser_variants)

Library usage Import the cleancss module and call the convert() function with a file-like object. Example: import cleancss with open('file.ccss') as f: print cleancss.convert(f)

Command line usage Call the cleancss.py without parameters to show the usage instructions. Pass any number of files to cleancss.py and the script will convert the files to CSS and print the result to the console. Example: python -m cleancss file.ccss > result.css