Bug: [dev branch] A small typing error makes jekyll serve break down

[Lost-MSth]

Description

In dev branch, running bundle exec jekyll serve can get the error: Error: $end-at: 20 -1-1 is not a number.

How to solve it

In common\classes\_var.scss line 77, changing code to $end-at: $end-at + $start-at - 1; can solve this problem. Just add a space.