Border displays as `NaN` in Light Mode

[DavidFrings]

Description

When setting Neutral – Vivid to 0, the border in Light Mode is rendered incorrectly, showing NaN in the first digit instead of the expected value.

Steps to Reproduce

1. Set Neutral – Vivid to 0.
2. Click Show Code.
3. Set to theme.
4. Scroll to Light Mode HSL.
5. Observe the border value in the first digit position.