That's perfectly possible, and easy, too!
Most resources you'll find online will suggest to switch to Jekyll Assets, which comes with a number of default plugins, including autoprefixer-rails. That, however, replaces the entire Jekyll asset pipeline, and requires changes in lots of places. A fairly high investment up front, just to get it working. Plus, the project appears to be dormant.
Continuing my quest to find a simple solution to a simple problem, I came across jekyll-autoprefixer, available as a Ruby Gem. Integrating that into my Jekyll workflow was embarrassingly straightforward:
Update the Gemfile to include the following:
gem "jekyll-autoprefixer", "~> 1.0.2"
Add the following to _config.yml:
plugins:
- jekyll-autoprefixer
Optionally add required browser support to _config.yml (e.g. for the latest 2 versions and Edge version 14 and up):
autoprefixer:
browsers:
- last 2 versions
- Edge >= 14
Note: You can alternatively supply a .browserslistrc file in the root directory.
Optionally enable CSS Grid Layout prefixing. This appears to be unsafe, and is disabled by default. You can either enable it from CSS code using a control comment (e.g. /* autoprefixer grid: autoplace */
), or globally through _config.yml:
autoprefixer:
grid: autoplace
That's all that's needed to integrate autoprefixer into Jekyll.