Add style on the website

[antagomir]

Comparing the miaSim website to mia website, we see that the miaSim site is missing page style.

• https://microbiome.github.io/mia/
• https://microbiome.github.io/miaSim/

Might be a bug somewhere, I think it used to have a style.

To be checked and added.

We can experiment with different pkgdown styles as well, if other nice ones are available.

[antagomir]

pkgdown manuals should tell how to add/fix style

[antagomir]

@ake123 could you check?

[antagomir]

Does not seem to work:
https://microbiome.github.io/miaSim/

[ake123]

Yeah it worked locally. I'll check it