Jekyll can't compile .sass files

Jekyll simply won't compile any of my .sass files when I run it with bundle exec jekyll build, but jekyll serve -l works just fine. It's really irritating, because my sass works in a development environment, but breaks if I upload it to Github pages.

The error:

Conversion error: Jekyll::Converters::Scss encountered an error while converting 'assets/css/styles.scss':
                  Invalid CSS after " 50px": expected "}", was ";" on line 3
jekyll 3.9.0 | Error:  Invalid CSS after " 50px": expected "}", was ";" on line 3

assets/css/styles.scss:

---
---

@import "base";

_sass/base.sass:

\:root
    --navheight: 50px;
    --backgroundcolor: #1b111d
    --textcolor: #F4F3EF
    --navlink: #2478ed

I'm pretty sure base.sass on line 3 is where it's breaking, not styles.scss. Not sure why the error displays itself that way.