I got the following message trying to build my site:

```
Dependency Error: Yikes! It looks like you don't have kramdown-math-MathJax or one of its dependencies installed. In order to use Jekyll as currently configured, you'll need to install this gem. If you've run Jekyll with `bundle exec`, ensure that you have included the kramdown-math-MathJax gem in your Gemfile as well. The full error message from Ruby is: 'cannot load such file -- kramdown-math-MathJax' If you run into trouble, you can find helpful resources at https://jekyllrb.com/help/!
Conversion error: Jekyll::Converters::Markdown encountered an error while converting '_posts/2017-05-15-first-blog-post.md':
kramdown-math-MathJax
ERROR: YOUR SITE COULD NOT BE BUILT:
------------------------------------
kramdown-math-MathJax
------------------------------------------------
Jekyll 3.8.5 Please append `--trace` to the `build` command
for any additional information or backtrace.
------------------------------------------------
```

I have to remove the reference to MathJax as math engine from my `_config.yml`

to make it work.

```
kramdown:
math_engine: MathJax
math_engine_opts: # more info: https://kramdown.gettalong.org/math_engine/mathjax.html
preview: false
preview_as_code: false
```

Does anyone know what is going on?

Thanks!