How do you generate smaller versions of hero images?

[sdondley]

I'm new to jekyll/ruby and I am building a site based on your theme: https://steve.dondley.com

Thanks for all your work. Theme looks great!

But I'm having trouble figuring out how to generate the smaller versions of the hero images. On mobile devices, I just get a beige color instead of a photo. I run npm run build before uploading the site to github. Not sure if I'm doing something wrong or not.

[sdondley]

NVM, figured out how to use a gulp command.