<span style="font-family:Microsoft YaHei;font-size:24px;">$(function(){
      $("#id").bind({
           focus:function(){
                if(this.value == this.defaultValue){
                      this.value = "";
                }
           },
           blur:function(){
                if(this.value == ""){
                       this.value = this.defaultValue;
                }
           }
     });
})</span>