The only codes that have a specific order are the link codes, which have to be:
a:link
a:visited
a:hover
a:active
However, if you have something defined twice, the second one will be what's applied. CSS starts at the top and goes down. So, if you had coding like this:
#about {background-color: #FFFFFF; } /* white background */
#friends {blahblahblah}
#about {background-color: #000000; } /* black background */
the black background is what would be applied even if you want the background to be white.
If that's not what's going on, check and make sure you didn't accidentally delete something and that there're no typos. Those are the most common reasons why coding stops working. Chances are, since you were moving stuff around, you probably accidentally deleted something, like a closing bracket.
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