All lines are double space

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See above? I hit enter only once for each number, but it didn't go the line just below, it went down like 3 lines.

I'm using Firefox version 31.0

Thanks

What I see is just one empty line between each one, which is the normal behavior when pressing enter here. It always leaves the space of one empty line before starting the next one. Is that what you mean? Because if not, then I don't see it here.

shift+enter

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Thanks guys!