方法一：
<div onmouseover="this.style.backgroundColor='#F4F9FD'" onmouseout="this.style.backgroundColor='#FFFFFF'"></div>

方法二：
<style>
.d_over{background-color:#307172;}
.d_out{background-color:#EFEFEF;}
</style>

<div class="d_out" onmouseover="this.className='d_over'" onmouseout="this.className='d_out'">哈哈哈哈哈</div>