Can't use $line-height-base for padding/margins

[tampakis]

Replace the $line-height-base references because they don't resolve to pixel values. Default value is 1.5rem.

[jrochkind]

Hmm, my understanding is that it's preferable to use rem values for padding/margin, so they are proportional to font size, for people that change their browser default font size (accessibility reasons).

But you are right that 1.5 doesn't work, it would have to be 1.5rem.

I think you want margins and padding to be just expressed in terms of rem. You don't need to use the $line-height-base variable, you can just write say 1.5rem literal. That will be 1.5 of whatever main font size is set to. In the Bootstrap 4 variables file, most padding/margin values are set in terms of rem literals like this.

You may have to figure out how many pixels these were meant to be (in previous Bootstrap3-based blacklight), and convert them to proper rem with 16px==1rem default. So for instance if it was 20px before, it should be 20/16 == 1.25rem now.