The following styled text looks right (as I wish it) in the editor but not when displayed in a browser on the Mac (Firefox) or PC (Internet Explorer).  In the first case, the font family is named in a span tag.  It does not take.  In the second case the font family is specified in a div tag, which appears to work.  The problem in not limited to incorrect display, since the editor formed these inconsistent and sometimes ineffective tags while I manipulated the normal view.

Impact -- bogus.
Impact -- correct.

Courier -- Bogus.

Courier -- Okay.

Okay, you can't see any font changes in the preview of the forum posting.  So here's what the problematic HTML looks like: 

<div style="FONT-FAMILY: Impact">Impact -- bogus.
<br/><span style="FONT-FAMILY: Impact">Impact -- correct.
<br/></span></div>

Here's how to demonstrate it for yourself.  Type some text in the default font, then select a different font from the pull-down.  Enter two lines of text, which appear in the requested font.  Then drag-select (highlight) the second line and specify the same font.  Examine HTML and see the situation described above.  Finally, view the finished text in a browser and note that the two lines, which should be in the same font, are not displayed as desired.

 

<span style="FONT-FAMILY: Georgia">
<div>Georgia is specified before typing and appears to work, <span style="FONT-FAMILY: Georgia">but only the portion which is highlighted </span>and styled manually actually gets the desired type face.
</div></span> 

By the way, this "incorrectly formed" HTML does look right when pasted into MS Word.