Almost. This would be better:

```
bfs ?= unit(base-font-size, '')
lhp ?= unit((base-line-height/base-font-size), '')
```

That snippet would allow for precision targeting of the `bfs` and `lhp` variables should one want to modify them without modifying `base-line-height` and `base-font-size`, and it removes the unit at the end of the integer so it's more consistent with all of your code below it