鼠标移动，修改背景图片

第一种方法：使用hover实现
html:

<div id="Library"></div>

css:

#Library {       background-image: url('./hoverBefore.png');       height: 22px;       width: 120px;    }#Library:hover {   background-image: url('./hoverAfter.png');}

第二种方法：使用onmousemove和onmouseout实现

<img src="./hoverBefore.png"      onmousemove="this.src='./hoverAfter.png'"      onmouseout="this.src='./hoverBefore.png'" alt="实况数据">