even and odd Selector
by Andrea Biagi
HTML
<body>
<p>The first paragraph.</p>
<p>The second paragraph.</p>
<p>The third paragraph.</p>
<p>The fourth paragraph.</p>
<p><b>Note:</b> Internet Explorer 8 and earlier versions do not support the :nth-child() selector.</p>
</body>
CSS
p:nth-child(even) {
background: red;
}
p:nth-child(odd) {
background: blue;
}