I'm trying to master the art of CSS, so I was examining a stylesheet. Most of it seems pretty obvious, but the are two things I don't get:
1. What does these lines mean:

.Content>p {margin:0px;}
.Content>p+p {text-indent:30px;}

2. What is the difference between a class and an id ?
For instance: <div id=menu> or <div class=menu>

Hope somebody can help me,

Thanks,

Ronald

An ID is a handle for that tag between it's opening and closing tags. Any JavaScript/CSS reference to that handle is applicable to the tags given that ID. A class on the other hand is defined inside the CSS style tags. A class is used when two or more items on a page display similar attributes (such as <p>, <h2> etc where you want all fonts to be black and 10pt and italic for example).

I don't know what the p and p+p means on the other bit. Never seen it before, but the .content is similar to having a.whiteLink where a is for the anchor tag and .whiteLink is the whiteLink class.