For the past 2-3 days, all the comics in the archives show up as blank. I did a little digging and I believe I found the bug. The HTML for each comic looks like:
Code:
<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAA4QAAAK3AQAAAAD1rLwhAAAABGdBTUEAALGPC/xhBQAAACBjSFJNAAB6JgAAgIQAAPoAAACA6AAAdTAAAOpgAAA6mAAAF3CculE8AAAAAnRSTlMAAHaTzTgAAAACYktHRAAB3YoTpAAAAAd0SU1FB+EKEBIXK734J3EAAABkSURBVHja7cGBAAAAAMOg+VNf4AhVAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAADfADWNAAEUSmyiAAAAAElFTkSuQmCC" data-src="https://static.sluggy.com/comics/900/171006e.png.pagespeed.ce.dB-a_aoW3I.png" alt="Comic for 10/06/2017">
I don't think Firefox 56 understands this format, with a data: URL and a data-src parameter. If I change it so the src="..." points to the static URL, then I see the image.
I don't know what the correct fix is, but if the person or people responsible for the web site could take a look at it, it would be most appreciated.