When installing the theme as a Ruby Gem its layouts, includes, stylesheets, and other assets are all bundled in the gem. Meaning they’re not easily visible in your project.

Each of these files can be modified, but you’ll need to copy the default version into your project first. For example, if you wanted to modify the default single layout, you’d start by copying it to _layouts/single.html.

ProTip: To locate theme files, run bundle info minimal-mistakes-jekyll. Then copy the files you want to override from the returned path, to the appropriate folder in your project.

Jekyll will use the files in your project first before falling back to the default versions of the theme. It exhibits this behavior with files in the following folders:

/assets
/_layouts
/_includes
/_sass

Additionally, from v4.5.0 onwards the theme-gem will also exhibit above behavior for /_data via a plugin. Consequently, the data files for UI Text and Navigation are also bundled within the theme-gem. This doesn’t apply if you’re building your site on GitHub Pages, however.

For more information on customizing the theme’s stylesheets and JavaScript, see the appropriate pages.