Currently, the Webflow Designer API only allows setting style variable values as plain numbers with a unit (e.g. { value: 1.25, unit: "rem" }). This limitation prevents developers from programmatically using powerful CSS functions, such as clamp() or calc(), inside custom properties via the API.

Adding support for at least simple CSS functions—like clamp(1rem, 2vw, 2rem) or calc(100% - 2rem)—would unlock a huge amount of flexibility for extensions, design systems, and responsive design automation tools.

Even if these functions couldn’t include references to other variables (e.g. var(--something)), being able to define static functional values would already be a significant step forward.

Why it matters:

• Enables programmatic generation of responsive type scales and spacing via clamp() or calc()

• Allows developers to use consistent, dynamic logic in custom extensions

• Greatly improves the design-system-as-code experience within Webflow

• Reduces manual copy-pasting of advanced functions into style panels