Baseline alignment?

[sbuys]

Want to clarify whether / how this library can be used to align to baseline grid.

Given a fixed capHeight, It seems like increasing the leading increases the vertical space above and below the text within its container. So in terms of establishing a baseline and vertical rhythm, what's the recommended way to think about aligning text to the baseline of a grid? Right now I can only get text to "sit" on a baseline if the leading is equal to the cap height.