http://www.tizag.com/cssT/float.php
We address this case by supplementing the previous rules with a rule that sets the text color to blue whenever an EM occurs anywhere within an H1:
h1 { color: red }
em { color: red }
h1 em { color: blue }
The third rule will match the EM in the following fragment:
<H1>This <SPAN class="myclass">headline
is <EM>very</EM> important</SPAN></H1>
A child selector matches when an element is the child of some element. A child selector is made up of two or more selectors separated by ">".
Example(s):
The following rule sets the style of all P elements that are children of BODY:
body > P { line-height: 1.3 }
Example(s):
The following example combines descendant selectors and child selectors: