v5.2.0

What's Changed

• Update csstree in #219
• Support @layer atrules in #221

Performance improvements

• do not pass around large objects if possible in #223
• Move some analysis to main loop in #225
• avoid getting property basenames if we can in #226
• Lower memory usage when comparing strings in #227

Full Changelog: v5.1.1...v5.1.2