• A CSS technique that uses custom properties (CSS variables) to create Boolean-like logic without JavaScript. When a CSS variable contains a space character (--var: ;), it can be appended to values without changing them, but when it contains initial (or is undefined), it forces the fallback value to be used. This enables conditional styling, AND/OR logic gates, and state management purely through CSS by toggling between space and initial values. The technique is attributed to Ana Tudor.

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