Alternate background colors for list items

How about some lovely CSS3?

li { background: green; }
li:nth-child(odd) { background: red; }

If you want to do this purely in CSS then you'd have a class that you'd assign to each alternate list item. E.g.

<ul>
    <li class="alternate"><a href="link">Link 1</a></li>
    <li><a href="link">Link 2</a></li>
    <li class="alternate"><a href="link">Link 3</a></li>
    <li><a href="link">Link 4</a></li>
    <li class="alternate"><a href="link">Link 5</a></li>
</ul>

If your list is dynamically generated, this task would be much easier.

If you don't want to have to manually update this content each time, you could use the jQuery library and apply a style alternately to each <li> item in your list:

<ul id="myList">
    <li><a href="link">Link 1</a></li>
    <li><a href="link">Link 2</a></li>
    <li><a href="link">Link 3</a></li>
    <li><a href="link">Link 4</a></li>
    <li><a href="link">Link 5</a></li>
</ul>

And your jQuery code:

$(document).ready(function(){
  $('#myList li:nth-child(odd)').addClass('alternate');
});

You can achieve this by adding alternating style classes to each list item

<ul>
    <li class="odd"><a href="link">Link 1</a></li>
    <li><a href="link">Link 2</a></li>
    <li class="odd"><a href="link">Link 2</a></li>
    <li><a href="link">Link 2</a></li>
</ul>

And then styling it like

li { backgorund:white; }
li.odd { background:silver; }

You can further automate this process with javascript (jQuery example below)

$(document).ready(function() {
  $('table tbody tr:odd').addClass('odd');
});

Try adding a pair of class attributes, say 'even' and 'odd', to alternating list elements, e.g.

<ul>
    <li class="even"><a href="link">Link 1</a></li>
    <li class="odd"><a href="link">Link 2</a></li>
    <li class="even"><a href="link">Link 3</a></li>
    <li class="odd"><a href="link">Link 4</a></li>
    <li class="even"><a href="link">Link 5</a></li>
</ul>

In a <style> section of the HTML page, or in a linked stylesheet, you would define those same classes, specifying your desired background colours:

li.even { background-color: red; }
li.odd { background-color: blue; }

You might want to use a template library as your needs evolve to provide you with greater flexibility and to cut down on the typing. Why type all those list elements by hand?