Recompute the type scale:
Given base (e.g., 16px) and ratio (e.g., 1.250):
- xs: base / ratio² (rounded)
- sm: base / ratio
- base: base
- md: base × ratio
- lg: base × ratio²
- xl: base × ratio³
- 2xl: base × ratio⁴
- 3xl: base × ratio⁵
Output: CSS custom properties and suggested usage per step.