when to leave space ,when not in CSS?

Question

This is ok(without space):

li.highlight{
    background:#FF9900 none repeat scroll 0 0;
}

This will not work(with space):

l         


        

Answer 1

You can think of li .highlight as having an implied * in it. It is equivalent to li *.highlight.

• li.highlight matches an li element with a class of highlight:
• .
• li .highlight with a space matches an element with class highlight which is inside of an li (a descendant): for example, the span in
• OMG NO WAY!