resize headings
resize headings

as per @rgaiacs suggestion
ErinBecker/datacarpentry.github.io,datacarpentry/datacarpentry.github.io,ErinBecker/datacarpentry.github.io,datacarpentry/datacarpentry.github.io,datacarpentry/datacarpentry.github.io,ErinBecker/datacarpentry.github.io,ErinBecker/datacarpentry.github.io