Just set the "max-width" of the image to scale based on the size of its container using % (so probably a "max-width" of 100% or something). That way if the container the image is in gets shrunk, it won't overflow out the sides. If you set the "max-height" then you should probably set that in pixels, but it probably isn't necessary to set it at all unless you have some really tall narrow images..
This is kind of the opposite of the sub-question you asked earlier, so the answer there still applies, just in reverse.
Oh, and FYI, I set up a Patreon account, like you suggested earlier, plus a PayPal donation link.
Anyways, I hope that helps! :-)