Hosted on Github Pages

Github will host their own files, but they don't deliver blobs with the
correct MIME type unless instructed to do so.  Anything hosted on a
branch titled "gh-pages" will be delivered as a persistent HTML page.

Just use the address:
<username>.github.io/<rep-name>/<html-file-name>

For example:
http://kylemit.github.io/otIntJS/just_array_please.html
Moved around files

For readability in your file structure, all javascript and css files
should be given their own folder.
Grouped items in CSS file

I'd include like items together in CSS and remove HTML.  Also order in
the way they will appear onscreen if possible.
Reordered functions

This seems minor, but you'd almost never see this in production code.
Functions should read like a book or table of contents from top to
bottom.  If you call another function, place it right below the function
that calls it.
Moved common function to separate file

Some of our business logic that we want to drive the application doens't
care if it's on page one or page two. We'd like to re-use as much as
possible.  This is why separating out DOM manipulation from our
functions was so important earlier.  That DOES make it care about which
page it's on.  Now that it's gone.  We can add these functions in a
separate file and include them before we start using them.

Step two, is incorporating into our other script file.
Replaced array script with updated base

Used updated base functions to sub out repeated scripts in array
practice.  Renamed consistent with file.
Remove obtrusive javascript
Removed Prompt

Prompt boxes have gone the way of the 8bit gif, blink, and marquee.
They are okay for test demos, but have no place in the modern web.
Users hate pop-ups and will try to ignore them and they poorly persist
relevant data.  Instead, just have a text box to store the value and
retrieve it.

In regards to copy, try not to use the word here for links and buttons.
It's not descriptive enough.  Of course it's here...it's a button.

See also: http://www.w3.org/QA/Tips/noClickHere
Calculate changes automatically

better yet, since everything is being done on the client and is trivial
for any computer, let's update results automatically on keystroke.
Since I listed the input type as a number (which provides the clicker),
we'll need to listen for mouseup events as well.