blid, im pretty sure my first reply actually is the answer to your problem... but i think you didnt look at the screenshot closely enough to spot the difference...
here i will again put two lines ... one is copied from yours, and one is the correct one that i have written myself so that you can spot the difference:
look very closely with the first line, it has an extra dot above the opening bracket < that i have circled for you..
the second line has the normal open bracket without the extra dot (or small line) on top of it..
now this is actually quite a weird thing to see, because i can only see this when i downloaded the page and opening it with Notepad++. I cant see this if i open with the normal notepad or viewing the source code through firefox... only with notepad++ (notepad++ is usually good at these things)
i suggest that you try to edit this particular page using notepad++ and you will see what i mean... then try to remove the open bracket and replace it with the one without the extra dot on top. the extra whitespace will be gone after that. i believe you are having a whitespace because the doctype tag could not be properly read by the browser (because of the problem mentioned above)