Making images responsive

How can I make the ‘figure’ shortcode create responsive images?

The figure is a figure with an img. You can add a css class to make it easier to select, but one trick would be to set both the figure and img to width=100%.

Pardon my ignorance as I am new to css. Is there a way I can set this within my local static folder?

Yes you can.

I will not go into a full tutorial here, there are documentation for this.

But I would suggest you start out with a Hugo theme:

Should both be good choices for responsiveness.

Have a look at the doc in

Set up a site, add a figure, see if it is responsive. If not, post your question.

Thank you @bjornerik, for the helpful responses. I found that in Hyde theme, poole.css is used to cause img to be responsive (by setting max-width).

I placed poole.css into my static/css folder and added the href to my header. Responsive images are now working for my site.

Once again, thank you so much!