To accelerate the download speed for readers with slow internet connection, the story content is compressed in Gzip format before transferred to your computer. Then your browser will uncompress it. Most modern internet browsers support Gzip compression. If your browser doesn't support Gzip, the content will not be compressed at all.
Some browser (an old version of FireFox) was reported to save the html page into Gzip format. Apparently, upgrade to the latest version fixed the problem.