@function

The @function CSS at-rule enables defining reusable custom functions with typed parameters and return values.

• •Functions accept arguments with optional default values and return types, providing type checking similar to CSS @property
• •The result descriptor determines the function's output and follows CSS Cascade rules for multiple value declarations
• •Custom functions can be nested within each other for code reuse and support comma-separated lists via the # syntax
• •Functions must return values only with no side effects, and browsers prevent circular dependencies between functions

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