htmlにテキストボックスのプロンプト機能を実装するための様々な方法

<style type="text/css">
.in_search {
border:1 none;
color:#999999;
float:left;
font-size:14px;
height:18px;
line-height:18px;
margin:3px 2px;
width:253px;
}
</style>
<input name="q" class="in_search" onfocus="if(this.value=='Please enter what you want to enter'){this.value='';}" onblur="if(this.value=='Please enter what you want to enter'){this.value='';}" onblur=" quot;if(this.value==''){this.value='Please enter what you want to enter';}" type="text" value="Please enter what you want to enter"/>