Some strange kind of hidden character has crept into lower. Make sure to type your code in a plain text editor, rather than something like Word. If you clear away the spaces and then add in returns again, they are both the same:
Code:<!doctype html> <html> <head> <meta charset="UTF-8"> <title>upper</title> </head> <body> <p>text</p> </body> </html>
I can't see any strange kind of hidden character through view-source.
I guess the editor has some kind of bug.
If I can see the strange kind of hidden character, I might fix the Editor.
Ralph probably just used copy-and-paste of the source code and its clearly sitting there on Line: 11 - illegal character data.