Changed help lightbox to tables and adjusted styles to fix Internet Expl...

...orer problems.

This pull request addresses two problems found in IE8 and IE11 (both in IE7 compatibility mode):

1. Script errors: turns out that the "style" element is considered read-only, so you cannot set its innerHTML property. If you set it to "text/css" type then you can changes its content via the cssText property.

1. IE7 and IE8 (possibly IE9 as well) does not handle the display:table[-cell or -row] CSS attributes, which resulted in those browsers treating them as having block layout. By recasting the lightbox content to a table (it is tabular, so that wasn't a conceptual stretch), I was able to make it look similar in all browsers.

I tested the changes on Chrome 31/Mac, Firefox 21/Mac, IE8/XP, and IE11/Win7 and there were no problems.