@Marc: Hi Marc, please do this for the sake of debugging ... download the files that accompany this lesson:
... unzip, and then open up my version of the html file. Does it exhibit the same behavior? If so, then I made a mistake in my video and I can look at it more closely. If it DOESN'T exhibit the same behavior, then you have some small issue in your code. That is a good place to start ... let me know what you find out. Good luck!