Just to add to my previous post.
I was watching another tutorial for work and it stated not to use Windows Notepad as a text editor for HTML as it sometimes caused problems and suggested Notepad++.
I downloaded it and opened the HTML file in Lesson03 and saved it as a new file (new name) choosing the html extension. There was no choice for UTF-8 format . BTW the previous Lesson03 file definitely had the html extension as that view is turned on.
Now everything works under IE.11 as well as Firefox with my scratch built CSS file.
Why it would work with Firefox and not IE.11 before with a scratch built CSS file is still a mystery. The original Lesson03 html saved in Notepad would work with the CSS file from the "After" folder.
I thought the problem was in the CSS file but apparentely it must have been a problem with the way Notepad saved the html file???
Anyways as long as its now working I'm happy.