Summary & Key Takeaways ​

• CSS lacks a native boolean type but supports true and false keywords.
• Custom properties can be registered to accept only these boolean-like keywords.
• The :has() pseudo-class can be used to flip these custom properties.
• Container style queries enable readable conditional styling based on these values.
• This approach offers a cleaner alternative to messy :checked selector combinations.

Our Commentary ​

This is a genuinely smart trick! I've often wished for more direct boolean logic in CSS, and this approach using custom properties and :has() is a fantastic workaround. It really shows how powerful modern CSS features are becoming, letting us write more expressive and maintainable styles. I'm definitely tucking this one away for future projects.