Color preview doesn't work with digit separators

When a color's hex value contains digit separators (e.g., `0xFF_F0_FF_00`), the color preview doesn't appear:

<img width="453" height="87" alt="Image" src="https://github.com/user-attachments/assets/4d5ccd7a-d54b-4161-ba89-3fd8292a683d" />