fieldset {
  width: 350px;
}

.textInput,textarea {
  width: 200px;
  font-family: arial;
  background-color: #FFFFFF;
  border: 1px solid #000;
}

.inputHighlighted {
  width: 200px;
  background-color: #FFCE31;
  color: #000;
  border: 1px solid #000;
}

/* Created by: Alf Magne Kalleland :: www.dhtmlgoodies.com (C) www.dhtmlgoodies.com, November 2005 */

var currentlyActiveInputRef = false;
var currentlyActiveInputClassName = false;

function highlightActiveInput() {
  if(currentlyActiveInputRef) {
    currentlyActiveInputRef.className = currentlyActiveInputClassName;
  }
  currentlyActiveInputClassName = this.className;
  this.className = 'inputHighlighted';
  currentlyActiveInputRef = this;
}

function blurActiveInput() {
  this.className = currentlyActiveInputClassName;
}

function initInputHighlightScript() {
  var tags = ['INPUT','TEXTAREA'];
  for(tagCounter=0;tagCounter<tags.length;tagCounter++){
    var inputs = document.getElementsByTagName(tags[tagCounter]);
    for(var no=0;no<inputs.length;no++){
      if(inputs[no].className && inputs[no].className=='doNotHighlightThisInput')continue;
      if(inputs[no].tagName.toLowerCase()=='textarea' || (inputs[no].tagName.toLowerCase()=='input' &&

inputs[no].type.toLowerCase()=='text')){
        inputs[no].onfocus = highlightActiveInput;
        inputs[no].onblur = blurActiveInput;
      }
    }
  }
}

<script type="text/javascript" src="highlight-active-input.js.js"></script>

<form method="post" action="#">
<fieldset>
<legend>Highlight active input</legend>
<table>
  <tr>
    <td><label for="name">Name:</label></td>
    <td><input class="textInput" type="text" name="name" id="name"></td>
  </tr>
  <tr>
    <td><label for="email">E-mail:</label></td>
    <td><input class="textInput" type="text" name="email" id="email"></td>
  </tr>
  <tr>
    <td><label for="comment">Comments:</label></td>
    <td><textarea id="comment" name="comment" rows="3"></textarea></td>
  </tr>
  <tr>
    <td colspan="2">
      <input type="submit" onclick="return false" value="Submit">
    </td>
  </tr>
</table>
</fieldset>
</form>

<script type="text/javascript">
<!--
  initInputHighlightScript();
//-->
</script>