This makes the rendered HTML appear equally-sized on both mobile and desktop displays.

Before	After

Notes

1. Although this is not present in the original $ python -m http.server command I found that there is a subtle difference between the simplehttpserver and python commands (on Windows at least) with regards to sorting of the listed files & directories, so I decided that it is acceptable for this difference as well.
2. I saw that the pythonliststyle_test.go imports are not formatted with goimports but I didn't want to clutter the PR.
3. I was tempted to do the same for the default server, but I saw the the Go FileServer doesn't return full HTML but rather just a <pre> tag. Adding a new handler just for that seemed like it would make the code harder to read for a diminishing gain (not to mention the possible slow-down).