| Software | Version(s) | 
|---|---|
| Operating System | macOS 10.14.6 | 
| jekyll | 4.0.0 | 
| ruby | 2.6.4 | 
The HTML and the SCSS it links to both have the front matter named "path" with the same value. In this example both HTML and SCSS have the front matter
---
path: /just_a_page
---
The front matter, "path", is used the HTML and SCSS
After executing jekyll serve in terminal, it return the error message:
  Conversion error: Jekyll::Converters::Scss encountered an error while converting 'just_a_page/assets/css/main.scss':
                    Error: Invalid CSS after "<": expected 1 selector or at-rule, was "<!DOCTYPE html>" on line 1:1 of main.scss >> <!DOCTYPE html> ^ 
                    ------------------------------------------------
      Jekyll 4.0.0   Please append `--trace` to the `serve` command 
                     for any additional information or backtrace. 
                    ------------------------------------------------