AjaxLine

There is a very intresting article about using the CSS for  decorating user input on websites.  Here I give one of the  examples from this article.

Use the :focus pseudo class to restyle users input
You can use CSS to make user input looks different when the user clicks on typing area and types something in it, using the focus :pseudo class. With it you can change borders style of you typing area like so:

textarea:focus, input:focus {
border: 2px solid #900;
}
All popular browsers supports it, so you can use it widely

The full article whith more example you can read here  CSS-Tricks