Add additional check for horizontal scroll compatability

[homerjam]

No description provided.

[benpickles]

Hey that's great, I hadn't even thought of horizontal positioning!

I haven't had a chance to test this out yet but I have a few requests for the commit (sorry):

• Don't bother generating the minified version, I'll do that when it's released.
• Ditto for updating the version number.
• Try not to reformat the whole document(!): it's changed from 2 spaces to 4; semicolons have been added to the end of lines; the preceding semicolon has disappeared; there's no longer a newline at the end of the file.

Otherwise, thanks for taking the time to put the pull request together 😄